OK....as far as software, all the software I used on my Treo 700wx that I installed on my Omnia work great. Some apps will have issues, but I find most are good to go. Let us know if you run into an app that appears to have issues and we can see what can be done to help.
If your thinking about using a backup file from one device to install on another....in theory it should work OK, but I would NOT suggest it....too much can go wrong behind the scenes!!!
The title of the thread mentions Sirius....are you looking for software to play it, or is that one of the apps your looking to see if it is compatible? (just in case your looking for software, look over here:
http://forum.ppcgeeks.com/showthread.php?t=26310 )