I'd think about paying retail to upgrade from my Trophy if Nokia:
-Upgraded the screen from LCD to whatever they're using on the 800/900 (Clearblack?).
-Storage space in phone was 16GB as opposed to 8GB.
-Changed the button on the bottom (back arrow, home, and search) to three separate buttons instead of the singular button it is now.
-More colors for the battery cover area.
-LTE would be a nice bonus.
The first two things I listed are the most important to me, the latter three I would like but could live without. That said, I highly doubt any 710 variant will be much different and the only thing on my list I could realistically see being changed would be the storage space.