Haven't tried it. I'm using postgres on a project right now and was looking at this as an option if I need to replicate my DB based purely on a description of its features (that was dumb, I know). I guess I'll have to rethink that now. Thanks for the heads-up!
If you think slony was bad then Burcardo will give you nightmares.
It's based on a brittle conglomerate of elaborate triggers - and it's effectively undocumented.
With something as complex as multi-master replication I'd think long and hard before trusting my data to a bolt-on hack like that.