The 780 will not allow custom graphics. You can get some custom graphics onto the 880, while the 980 will give you the most freedom to put what you want on it. The 780 does not have the motion sensor to turn the screen on. You will have to press a button to wake it up. The hard buttons will work without having to wake it up, while the "soft buttons", you have to press first to wake it up and then again to send the command. As for the speed in which the remote flips between pages, I find the 780 and 880 to actually be faster then the 980.
Also, the 780 uses 4 double A batteries, while the 880 is rechargeable with a power cord you have to plug into the bottom, and the 980 is rechargeable with a dock you place it in. While there are ways to work around the limited amount of pages, I have never had an issue with the amount of pages available. The goal is to steamline everything while keeping it nice and clean. All those buttons that never get used do not need to be on your remote. Keep it nice, simple, and clean.

In all honesty, and of the remotes will be an upgrade over the 700. CCP will offer a lot of programming benefits over the old 700 Editor. The Database Navigator alone will help you program the remote and keep it clean.