With Galera now somewhat supporting MyISAM replication, does that also mean that it will replicate Aria databases with storage engine (which is more or less feature complete to MyISAM, and a drop in replacement). Are there any special configs I need to watch out for to make this work (such as wsrep_replicate_myisam=ON) ?
Apparently not, based on this recent post which suggests that they didn't open it up to non-transactional engines, but specifically for MyISAM... and even as such, it's still experimental (and still seems like a horrible idea except for the extremely limited case of the DML manipulation of the tables in the `mysql` database).
The article "5 Tips for migrating your MySQL server to a Galera Cluster" is over a year old by now, but it seems unlikely that this statement will ever be modified by much, because of the nature of how the internals operate:
Please be adviced that this is an experimental feature, and as explained above, will never really be able to work as well and perform as well as using InnoDB tables. It's dangerous in many other ways too: for example non-deterministic functions are not protected for in any way (ie it is even more dangerous than SBR in MySQL classic replication). Still, this feature has turned out to be helpful for some users, for example if applications do occasional updates on some of the MyISAM tables in mysql.* database, which of course can't (yet?) be migrated to InnoDB.
So apparently the real motivation for tying in to MyISAM wasn't because it was a good idea, but because that's the storage engine of the mysql grant tables, which does make quite a bit of sense depending on how you access them.
Yes, Aria seems generally a safer place to put your data than MyISAM but it's still not transactional like InnoDB/XtraDB, and I fail to understand why anybody wanting the resilience of a cluster would avoid InnoDB, which is, you know, sort of exactly what Galera is actually for... other than the one or two things MyISAM and Aria have that InnoDB doesn't... which are spatial and fulltext (pre-5.6) indexes.