lol!
Ermine is faster (I think) and has Android 2.2 (Froyo) which gives us more possible apps. Also, the User Interface got a bit nicer, IMHO.
Disabling javascript in the browser keeps it from crashing 98% of the time.
You don't have to reregister with enTourage. The only thing you might have to do is register with Adobe for the DRM, which you can do through Adobe Digital Editions on your computer (connect the USB cable). I believe the instructions are in Obsessed's New User thread (sticky).
I
think (haven't tried it) that you can copy apps to your SD card by doing an app backup, then copying the .apk files from the Backup folder onto your SD card using ES File Explorer. Not sure if they will run from there, though. I kinda think they won't.
Good luck!
If you decide to try anything, I suggest you read first, proceed when you're fairly confident, and stop to ask questions if something seems wrong.