Having owned a 700p in the past, and now an owner of a 755p, I can say for sure the 755p is a more attractive, feature-rich phone. The latest firmware update for the 755p claims to add stability and speed with ROM update 1.07, so to me, it just makes sense to get a newer device. They are both running Garnet OS 5.4.9. The 755p adds a Sprint-branded IM app, for AOL IM, Yahoo and MSN, which is nice for me. It also has Google Maps. The 755p also has a rubbery-grip to the back of it, which is a real plus for me...I haven't dropped it in six months. I also think the 755p has better sound, which is very important to me--the 700p had OK sound, but I had to purchase software to increase the sound...which I shouldn't have to do.
This is the best side-by-side comparison I've seen yet:
http://gadgetsonthego.net/2007/05/tr...treo-700p.html