When ogling with acquiring a system camera for UW use, I think one must consider that the camera body itself makes up only a small part of the entire budget. Therefore many UW-photographers go for a model that is very high up in the camera body hierarchy (to have the best performance and the longest time for using it). Some 1-2 k$ more do not really matter, considering an entire investment of 10-20 k$ (lenses, (dome)ports, extensions, flashes etc...) . Why not opting for Z8, what most Nikon photographers do now?
This is exactly right as I have learned a while back.