I am going through this process. I can almost guarantee that the Power 6
has hardware that 7.2 will not recognize.
I did host some guest lpar's of 7.2 underneath a 7.1 host lpar. Yes it
still generated some warning messages about the underlying hardware having
some cabling loops that it didn't like but it worked. Best make darn sure
that that whatever hardware you do need by the 7.2 lpar is carefully
thought out. Like, you're not even thinking about using a scsi tape,
right? And if it's fiber it's on an IOPless controller on the main unit,
right? I'll be honest, the ancient hardware I had, and the draconian
restrictions of 7.2, put a serious crimp in my style of having all lpars
on the latest release within 3 months of G/A.