I went to my LBS yesterday with the intent to buy a 3900 for myself and a 3700 for the wife. The bike shop was running a sale and I ended up with a 4500 for myself and a 4300 for the wife. The 4500 was $399.95 and the 4300 was $349.95, I couldn't pass it up.
So far the 4500 is awesome except for the saddle... Wow, what a pain in the ass, literally. I did only 3 - 4 miles yesterday and my ass is killing me. Any recommendation for a saddle?