This is a bit of an update, and just documenting my process given it may prove useful anon.
So, when @timmmmyboy told me MyISAM database type will not work with the Gallera database cluster, I switched the type for both bavatuesdays and ds106 to InnoDB. This did not cause a load issue for the bavatuesdays cluster, but the ds106 database was tripling resource/cloudlet usage. This weekend I got some time to try and revert ds106 back to MyISAM and the resource/cloudlet usage was cut by 2/3 at least. So, something is amiss there, and given Gallera Cluster is not doing anything with MyISAM, I might as well try and move ds106 to a non-cluster WP environment.