I did a clean install of 1.9, everything works fine I can install apps but as soon as I load the Tablet mod the phone just reboot every time I want to install something. Seems like some incompatibility in Tablet mode.
Anyways I'm still on 1.9 running in normal mode and everything is working as it should. Don't see a need to waste bandwidth to upgrade to 1.9.1, will wait until there is some big changes or maybe even a port of the S3 rom.
Now that sounds Healthy...I'll probably be doing the same