We've got a couple five-fingers in the house. I have injinji socks, and I have these. These are awesome. Are they as good as injinji socks? Since Injinji socks are laced with solid platinum, I would say n.... What? Injinji socks aren't laced with platinum? Oh...so...what's the big deal about injinji socks? Nothing. Injinji came first. That is all. These are great, too. Moisture wicking properties are nice (and sorely needed with five fingers shoes).
Are you a cotton-is-king type of sock consumer? Well, we're all entitled to our prejudices. I would argue, though, that a quick glance through modern athletic-wear textiles and technologies would have you reconsider your luddistic ways; cotton sucks, if you're sweating.
edit: size-wise: I'm 'a size 8, which is at the top end of sm/med. I fit 'em fine. my SO is a size 5, which is at the small end of sm/med. It's juuuuust small enough for her. SooooI'd say it's pretty size accurate, although there's no telling whether you have huge fat toes on your size 8 foot.