Perhaps I should have asked it differently. My main consists of mirrored VDEVs. Also, my main is encrypted, and I’m planning to use raw replication (to an offsite RAIDZ). I’ve heard of some fancy issues with raidz and wasted space. Can raw replication from mirrors cause those?
Regarding the redundancy – I think I’m ok with raidz1 for offsite, as it is kinda unlikely I would ever need it.