Occasionally, I make a backup of the existing library on disk before performing the update. That way, I can just go back if something significant in terms of issues occurs. I think we've really only seen a problem once or twice.....and it's been a while since that happened.
Future PSR-900 user...(still hoping!)
PSR-800 x 2 | PSR-500
BCD-396T | BC-296D (voice) | BC-245XLT (mTrunker) | BC-600XLT | BC-IV | VX-8R
Not a Radio Shack fan.....