OK, I have the beginnings of an answer here.
A bit of tracing shows that Rhythmbox’s parser doesn’t recognise the ‘aeSP’ (com.apple.itunes.smart-playlist) content code, causing it to bug out before it reads the ‘minm’ playlist title (which later causes it to give up on the playlist altogether).
I’m not entirely familiar with the DAAP protocol yet so I’m not sure if Rhythmbox is meant to ignore that entry and continue parsing. Let me grab some documentation.
Edit: OK, here’s the problem. I think Rhythmbox developers were a bit lazy and didn’t bother to request ‘/content-codes’ for the correct dictionary. Instead, all of the content codes are hard-coded which means they cannot parse any code newer than the ones they have (because they don’t know it’s size).
The correct solution is to implement a /content-codes parser, which I will suggest, but don’t have the time to do this myself. So instead I’ve added the offending content code into a hard-coded patch and will submit this upstream with the aforementioned comment.
http://www.jcornwall.me.uk/patches/rhythmbox-aesp-daap.patch