Welcome to TE, both of you!

Personally, I'd be a bit wary of buying a used carbon frame without knowing the history. (Has it ever been crashed?). However: Make sure it fits, first off. It can look like a great deal, but it's a terrible one if it hurts to ride! I have an Avail 3 (she's my baby), and I'm seriously considering upgrading the components so I can keep her as my backup bike. You can tell the difference between Sora and 105--the shifting is smoother, the derailleurs don't need to be tweaked nearly as often. The carbon might smooth out the ride a bit if your roads are rough/chipsealed.
If you're happy with the fit/frame, there's always the possibility of upgrading your components, but I think by that point you may as well buy a new bike!