I have the 7.4fx. This bike was made for Scheels and comes in a nice matte tan color that I have not seen on any other Trek bike. It has the hydroformed aluminum frame that comes with the 7.3 and up. If you have not seen this frame it is really something. It has nice curved lines and the tubing is slightly triangular instead of round. Most of the components are the same as the 7.2 model.
I also have Trek road and mountain bikes. The fx has a fairly aggressive riding position so you can get low and out of the wind and also put alot of power into the pedals. I like the fx for city streets and bike paths, both paved and hardpack. I spend most of my time on hard surfaces so I replaced the bontrager invert tires with schwalbe kojak slicks. The slick tires offer a much smoother ride. I like the 35 mm tires for cushioning bumps and navigating inconsistent surfaces. The fx also performs fairly well on the open road. Not like my road bike but I do like to use the fx for short road trips because I find it more comfortable.