I'm tentatively marking this as an OS X issue as the xattr I'm failing on is Mac specific, but it may be an incompatibility somewhere else.
Basically I'm running the following command:
> sudo /opt/local/bin/rsync -rultxX -vih --delete-during /foo/bar root@remote:/foo/bar
However, I'm receiving an error as follows:
> [sender] internal abbrev error on Macintosh HD/opt (com.apple.FinderInfo, len=32)!
> rsync error: protocol incompatibility (code 2) at xattrs.c(682) [sender=3.0.9]
Which then causes rsync to abort early.
Just wanted to note that this issue can still occur, and I'm still at a bit of a loss as to what is causing it; it's being reported as a protocol error, but it can happen even when performing a transfer locally (no possibility of a version mismatch).
There are 2 xattr fixes coming in 3.2.3 that have a good chance of solving this. If it's not fixed, feel free to reopen.