No, I have not listened to any current or recent Pioneer in-wall speakers (save for the speakers Pioneer used for its Elite plasma televisions up until 2011), and those were certainly a step above what most television manufacturers used.
As Sound & Vision mentions in its 2009 review, Pioneer did design and sell a high-end speaker system, the TAD Reference line, beginning a few years ago (I never heard them personally), and for me, that tells me some of the R&D that went into those speakers likely trickled down into their mainstream offerings over time (Paradigm, PSB, B&W, Monitor Audio, and others would migrate the tech developed in their top-end products into their lesser products within a couple years of the new tech having been developed).
Certainly I prefer a 3-Way speaker whenever possible, and I do like a concentric design (a tweeter recessed in the center of a mid or mid/bass driver) as well as dual woofers considering architectural speakers struggle with lower frequencies (largely because they have no enclosure, but that can be remedied).
Sound & Vision gave a modestly favorable review to these speakers when Pioneer sold them for $5-700/each, so at $129.00, the value versus price appears pretty good. I cannot think of a 3-Way in-wall speaker with dual 5.25" woofers that could be purchased for $258/pair from a known manufacturer. The only comparable speaker in this price range that I can think of would be the NHT IW2, and the design is certainly less aesthetically pleasing than the Pioneer (the IW2 has also been discontinued, but it was my go-to $300/pair speaker, primarily for music rather than movies, and features a 3-Way design with a 6.5" woofer, a (2) 1.5" mids and (1) .75" tweeter). Again, the NHT was a better musical speaker than a surround sound speaker, so not exactly apples to apples here.
That all said, Pioneer is known first and foremost for its displays (even their Sharp-made Elite LED LCD is a phenomenal television), and second for its Audio/Video receivers. Speakers, not so much. I think these speakers would sound good, I think the price is reasonable, and I think that as long as you do not expect to ever resell these speakers (used architectural speakers are difficult to resell regardless of circumstance), then most anyone would be happy with the purchase of these.
When I am looking at purchasing any product, whether a couch or in this case, speakers, I try to purchase speakers from a company whose primary focus is speakers, just as I purchase a digital camera from a company who is known for manufacturing cameras. Sure, Samsung makes a digital camera, but both Canon and Nikon have more experience and generally make a better camera dollar for dollar than Samsung does. Same thing with Pioneer. Pioneer makes one of the best displays (and used to make the best display up until the very last Elite plasma) of any mainstream manufacturer (I am not including Runco of course), and they make a pretty darn good audio/video receiver as well (I have been very disappointed with their Blu-Ray players lately however). As for speakers, they make them, just like Samsung makes cameras, and neither is a bad product, but that is not Pioneer or Samsung's strongest suit. The attraction here is, for $129, are you getting the performance of a $700 speaker as Woot implies? Probably not, but for $129, I don't think you'll find anything else that performs as well as these speakers will for the same amount or even 50% more.
My only other caveat (after I typed everything before and after this paragraph) is the size of your room. 30' x 17'? These are a little on the small side given the cubic air volume in your media room, and so I strongly recommend building an enclosure inside the wall where these speakers will be mounted. You do not need to rip apart the wall or even cut out more drywall than you already need for mounting these speakers, but using drywall screws and some ingenuity, you can build an enclosure in the wall around these speakers (easier to do in a ceiling, I know, but entirely possible in a wall).
When installing an in-wall (or in-ceiling speaker) if it is possible to block off part of the wall (using 2x4s or 2x6s depending on depth of the wall/ceiling) and line the "enclosure" with a layer of foam in order to create a cabinet, it will result in a better low-end response from any architectural speaker. As for the volume of the enclosure, I cannot say what dimensions would work best for these speakers, but any enclosure is better than relying on existing home insulation and layout of the stud bay.
For the center, if possible, shop at a local A/V store where you can demo different brands of center channel speakers in your home to see which one sonically matches these Pioneer in-walls. When I managed a local independent for 6+ years, I would allow my clients to take home any of my floor model speakers (with a deposit that covered the full retail cost of the speaker of course) for several days at a time to listen in their own home. I would listen to an acoustic/vocal recording using a "5-Channel Stereo" listening mode on your receiver (amplifies a 2-Channel source through all 5 of your speakers), which will be the easiest way to hear how well a different manufacturer matches these Pioneer in-walls.
For a subwoofer, wattage does make a difference in how well the amplifier can control the actual driver, and the more power, the better the control. Personally, unless I am spending thousands of dollars (of my client's money), my preference is a single 10-12" driver with 3-500 watts of amplification in a front-firing sealed enclosure (ported enclosures result in more sound but less accuracy than a sealed enclosure and downward firing drivers are less desirable, especially in carpeted rooms). Although I have not listened to very many SVS subs (I actually became a dealer of SVS several years ago but only so that I could ship them to Hong Kong; didn't make as much money as I hoped at the time), they are very highly regarded and reasonably priced. The SB-1000 is a sealed 12" 300-Watt sub for $500 that performs quite well, although again, I'd prefer a little more amplification for a 12" driver.
If you have the money, especially given your room size, it is actually preferable to use two subwoofers given that most rooms, depending on size and configuration, have "dead zones" throughout the room in which the low frequencies are unable to resonate. Although I recently installed a James Loudspeaker 1000PT-M 10" Passive Subwoofer underneath a client's family room piped into a HVAC vent in the floor, and paired with a James 1000-Watt sub amp, this thing crushed the entire room with a phenomenal low end and no discernible dead zones, which surprised the heck out of me and left my clients eager to show off their system to anyone who would listen. However, that was $3,000 plus install costs. :-( But it was certainly worth every penny (both Lebron James and Dwayne Wade use James Loudspeaker in-ground subwoofers for their outdoor speaker systems, with Wade opting for 21" drivers).
I am also impressed by Paradigm and PSB, both of which in addition to making great speakers, have separate yet related audio component companies (Anthem for Paradigm and NAD for PSB). The newish Anthem receivers by the way (starting at $999) are phenomenal products that sound incredible for the amount of money (partly due to their toroidal transformers), but also because the Canadians make great audio gear. Back to my philosophy of buying speakers from a speaker company, you not only have a company proficient at manufacturing drivers, you also have a sister company proficient at manufacturing the amplifier for those drivers. The result is a great product for the money, and if you can find a dealer (or online seller breaking its dealer agreement) willing to discount a Paradigm or PSB product, then they are certainly worth taking a look at.
Another long, drawn out explanation, but I am playing the role of a caretaker for a dear friend who shattered his femur after plummeting off a client's arbor (the wood had extensive dry-rot that the client had covered with paint and failed to disclose to my friend that this was the case), and thus I have plenty of time as I help him transition on his first day out of the rehabilitation hospital.
Enjoy setting up your media room and I'm curious to know how it all turns out!
BTW have you actually heard any of these speakers especially the Pioneer S-IW571L 3 way? Just looking for your opinion. My media room is 30'x 17'. Thinking of getting 4 of these 3 ways for fronts and sides and 2 subs and a CC.