You should be able to migrate your data to the new Tungstens. The screens are really nice and the units are faster, plus you get an MP3 player and Bluetooth- I'd upgrade rather than spending money on the m515 repair.
I've just upgraded from my old Vx to a T3. V good move & had no problems with the upgrade. Some old apps from my Vx were installed on the T3 as part of the first hotsync & caused crashes when run, so I just deleted them (and didn't miss them!).
The updates to the calendar & contacts apps are welcome. I had hoped for more control over Hotsync with the new version, though.
The landscape screen is more than a gimmick. I use spreadheets on my T3 (mostly to read, rather than edit) and the horizontal format is really useful.
I can't see the point of the MP3 Player aspect (not enough memory - I'll stick with my iRiver), but otherwise, it's a very cool toy, sorry, business tool.