Titanium has a lot of options (haven't used MyBackup), all apps, all system data, apps + user data, move apps to SD etc to the best of my knowledge doesn't touch the base OS. Suggest you have a look, I used all apps + data and upon restore it asks for reinstallation of each app so you can pick & choose. You could do a trial run by doing a backup on 2.1, deleting something that is easily restored via the market, then doing a restore while still on 2.1. After that do a backup to the SD card that you intend to run with 2.2(ie not the card you're flashing with) install 2.2 root the device download your prefered backup program from the market and do the restore. Seem to be fairly straight forward for me.