This is a great post! I really like your story of change-over from chem photog. because it gives me hope. I have been trying to do this after years of reticence and I am going CANON. I have just been through about a month of nightmares trying to purchase and build a kit, dealing with crazy people; Salesmen right out of David Mammet's GLENNGARY GLEN ROSS, and great deals with sketchy websites. Lost my money once but got it back again and had to cancel my credit cards on a second occassion of bait and switch sales. But I've got to expand my abilities and go pro. This is the only place I feel safe. Is there a reason the Canon Mark IV doesn't seem to be readily available with UW housing or why other models are preferrred? Is it all about $; being that M4 is a high end camera will not sell as well or is it a bad choice as an UW camera? It seems to be the perfect camera for me, the versitility I would want; an art camera that will work wonderfully for stills, news clips, UW and short film. I would like to be pointed in the right direction so I can go dig my money up from the benthic regions (joking) build my kit, and get to work.