So, I'm considering a new Trek FX, and am trying to choose between the 7.3 and 7.4. According to Trek's website the main difference is a different model of geartrain (same speeds), and an aluminum fork on the 3 vs. a carbon fork on the 4. The guy at the shop recommended the carbon fork, saying it's better at shock absorption than the aluminum, but I also don't doubt he was just trying to sell a $150 more expensive bike.
I ride mostly on pavement, with some crushed limestone types of paths, though this being the upper Midwest we get some bumps and frost heaves, so I'm not exactly riding on a pool table. Am I going to really feel a difference between the carbon and ally forks? Is one going to be longer lasting than the other? Enquiring minds and whatnot.