I have an old MacBook Pro running Snow Leopard and iTunes 11.  I have a spiffy new retina MacBook Pro running Mountain Lion and iTunes 10.  The abomination that is iTunes 11 was released after I got the rMBP, and I never upgraded it.

The old MBP is the machine that is the one that syncs with my iPhone.  It has my portable iTunes library, as well as my photo library.  I’d prefer to move everything over to my spiffy rMBP, but I also don’t want to have to upgrade to iTunes 11 on it.  I also don’t want to lose all of the metadata that I have stored in my iTunes library, such as playlists and song ratings.

I’m not trying to downgrade iTunes 11 on my old MBP.  My iTunes library has been updated multiple times (new songs, new ratings, new playlists) since I unwittingly accepted that update, so I don’t think that any of the downgrade options will work for me.

iCloud syncing is very much not an option, not least of which because my iTunes library is larger than its limit.

I realize that I’m asking for a lot here, but I’m hoping that someone might have done this and my search-fu just isn’t awesome enough to have found the documentation of it.  I’ve found plenty of documentation about downgrading, but not my scenario.

An alternate scenario would be for me to start syncing with my server at home instead of syncing with my laptop.  I haven’t pursued this seriously because there are multiple iPhones in the house (mine, my husband’s, and our household line) and I haven’t found a good solution for dealing with one iTunes library, multiple Apple accounts (and the resulting differences in which apps are available where), and multiple iPhoto libraries.  We currently have the home media server set up with a shared account (which is what is used for adding new content to the iTunes library and all playback), and we have individual accounts on the server.  Apple’s guidance for using multiple devices on the same computer is useless for this household’s use case.  So unless there’s an awesome solution that I haven’t found, it seems like it’s a lot easier and less error-prone to maintain my own iTunes and iPhoto libraries on my own laptop.