I have a 09 2.1. You are right in the major differences are the 09 frame vs 10 105 group. I am also a convert from a hybrid/mtb. In the 8 months I have had my 2.1 it was been flawless. It is in the shop right now for a 2K mile service. The rider makes the most difference not the bike. There are fast people on steel and slow people on carbon.

The most important factor after fit is which bike you do love? You want to buy a bike that beckons you to ride to at all times. If you do not love your bike because the color is not right or the wheels are wrong, you will find reasons not to ride. Any spare time I have, i will sneak a ride on my 2.1. To many people it is only a Trek 2.1, but that was the bike I wanted.

Good Luck.