Hi,
I'm using MJ 12.0.49 and just bought an iPod Classic 120 (model code MB565, firmware 2.0.1 PC).
I had been playing with iTunes 8.1.1.10 and synced a copy of my library to the iPod without issue.
Then I made a separate copy of my library (which originally came from MusicMatch on another old PC). I fiddled about with the tags a bit and downloaded some missing art and then tried to sync to the iPod after disabling iTunes auto sync.
http://i43.tinypic.com/2l8xe6f.jpgThe above warning box appeared saying that there was a data incompatibility with the iPod. To be safe, I reformatted the iPod and then did the sync of the alternate library from MJ12 and this time there was no problem.
But I'm wondering if there are any gremlins that I might find later. The iPod seems to work ok but just curious about whether Apple changed something in the data spec. for this firmware revision (which requires iTunes 8 to work properly itself). I guess it could be something to do with the new "Genius" feature on this iPod.