Having a Trek 7.5 FX myself, I highly recommend the model. I believe the frame geometry is the same as that of the 7.0 FX, but the 7.5 FX has components that are more tuned for faster rides on the paved roads - 700 x 28 tyres, double crank (as opposed to triple), carbon fork, etc. I've racked up about 500 miles since I bought it in mid-August. I ride on the crappy Seattle roads, and the tyres + the rear shock absorber built-into the frame work very, very well. I'm a happy cyclist.
My wife has a 7.4 FX (WSD) and is also very happy with it.
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The value of your life doesn't change based on the way you travel. - Dawn Schellenberg (SDOT)