I think I want to buy a Trek FX. I am torn between the 7.3 or stepping up to the 7.5. I am approx. 250 pds. and those wheels on both seem so flimsy looking. I know the 7.5 would feel quicker, but is the alloy fork on the 7.3 reallt the smarter move for a heavier rider? I am looking for comfort up to 20-30 miles, not so much on speed. I also saw a GF Marlin mountain bike right next to them in the showroom and I wondered if putting slicks on something like that would be better? i looked pretty sturdy but I guess would be a tank on the road?