All I can say is make DARN sure you do a manual backup of your device before you install this.
I just installed it on my Tour w/ 220.127.116.11 OS and it totally hosed my BBM. It showed installed in the app list, but no icon anywhere (and not hidden).
Tried to 'downgrade' back to .33, and have no contacts or groups. I also could not restore my contacts from the backup that BBM can do. There are backup files on the media card (can see them via mass storage mode on my laptop), but the device doesn't see them at all.
I foolishly thought I still had a device backup from my upgrade a few weeks ago, but it's nowhere to be found (lesson learned). So now I'm re-adding everyone manually.
No longer a BES Admin, but it was fun while it lasted!