Thanks Giles much appreciated. I haven't noticed any performance lags with the ZWO CCD driver so far so maybe I've been lucky (or am using small files w quick downloads, since not a full-frame camera).
Hmm, I'm guessing these multiple individual camera drivers couldn't also be used for multiple instances of EKOS (ie if one Pi was connected to two camera+mount combinations)? Or could it be? (For example, an EqMod mount with 2 ZWO cameras & an iOptron mount w a ZWO camera)?