Until I got my Pista Concept (or actually until I realized that one was within my grasp for cheap) I had my eyes firmly set on a TK2. Great looking frame!

Riding this concept around town before I actually bought it (now its just a frame and fork hanging from my ceiling) I immediately noticed what everyone else has always described about regarding the stiff aluminum frame and the tight geometry. Right now I ride a steel, somewhat relaxed, frame and have gotten pretty used to it. The Concept wasn't exactly uncomfortable for me (keep in mind this was a short ride) but I definitely felt every little teeny bump and imperfection in the road.

The track geometry offers a "twitchier" ride too, so it reacts faster to small movements. A TK2 for $500 sounds pretty neato... but a steamroller sounds great too. I think at some point though you get used to what you ride and it doesn't really matter. Just play with both and whatever you feel better with is what you should do Sleep on it first though!