I had my Trek 7500 since May. I think it is a great bike to start riding. And, yes , after 5 months of riding it I also think about upgrading to real road bike. I also have Trek 4300 that I bought mid-summer and that one is going to be a keeper for mountain trails around Chicago.
Good thing about 7500 is that you can improve your fitness without sacrifice of the comfort. I will be selling 7500 after I make my choice about road bike - you can send me a message if you want to buy used 7500 ( size 22.5"). I usually do 60-70 miles a week so bike probably has around 1200 miles on it. I am in Chicago NW burbs.