Alison - I've switched over to PPRo as my primary editor. If you're moving to CS6, you probably won't look back once you move. It's easy and as Jessica said, you can easily map all the keyboard shortcuts to be your usual FCP settings. But even if you don't the PPro shortcuts aren't hard to pickup. I recommend downloading the 30 day trial from Adobe and try kickin it around. I think you'll be surprised.
As for FCP7, it's dead software. Apple has moved to FCPX and they are not developing, patching, or supporting FCP7 any longer (or Color, DVD Studio Pro, Compressor 3, etc.). So there is no guarantee how long FCP7 will continue to work on an Apple machine. I've heard that FCP7 still runs on the newest OS Mountain Lion, but again it isn't supported. So you're only one Apple software update away from FCP7 failing to launch. Technically the last supported OS build for FCP7 was 10.6.8 - Snow Leopard.
I suspect that FCP7 will continue to be used for the next several years, but people will start moving to other software - Avid, PPro, Autodesk, or FCPX. Given the amount of choices right now as an editor you can pickup any NLE software from the big A companies and it will run on a current gen Mac.
Ryan Holmes
http://www.ryanholmes.me
vimeo.com/ryanholmes