I bought the Ascender 22 for the same price the last time they were on Woot. The chassis IS included with the Ascender 22.
This bag is AWESOME! I travel for work all the time and I get compliments on my bag from fellow travelers, flight attendants, pilots, etc. The bag (with chassis) fits in the overhead on most 737s (all Southwest planes). On some small "commuter" jets I've had to gate check it if it was going to be a full flight, but it usually fits.
I love it. Now...do I need to get one of the other bags....hmmm?