Non-destructive update via Sachesi... no loss of data and while they warn to backup just in case I never have. It's so simple... download Sachesi, open, plug in phone, close Blend, put in device password, then it'll give you the latest update like an OTA one. When I had to do this I thought it would be a pain, but I was installing an OS released by BlackBerry so I didn't consider it a leak and it was so easy. Will never wait for an official OS again!
Note: Please see the leaked OS threads in the forum. This is in no way a full guide.