I took a housing and strobes into/through a hydrogen sulfide layer once in a cave in Mexico and the while the housing seemed unaffected (Ikelite at the time), all the fittings turned a dull grey colour as a result of the exposure. Apparently the Hydrogen sulfide reacts with metal ions to form metal sulfides which are often dark in color. I also noticed the same thing with my suit zipper and the metal fittings on the strobes. While my photo gear didn't look as shiny afterwards, there doesn't seem to have been any negative, long-term effects.
I now have an Aquatica housing, and while I haven't exposed it to the H2S, yet, I would think the same would happen - exposed fittings may turn dark, but the coated housing should be fine.
Wow! For the first time with a camera u/w you did a fine job! They all seem to be colourful, sharp and well-exposed. Nice work. I'd also point out that you did (in most cases) exactly what is most often recommended by folks that know fishes - get down on their eye level. I realize the lionfish image is a take that most can appreciate despite it not facing the beast. I really like the cornetfish image.
I'd say now you're faced with the challenges we all are... timing (right place, right time), patience (for the "peak of the action" as Martin Edge says) and trying to blend in while getting close enough to the subject looking back at you!
I'm with Eric and divengolf. Up until two years ago I was shooting a Canon 30D in an Ikelite housing, then moved to a 7D and Aquatica housing mostly because the old rig was holding me back in a practical "user comfort/safety" kind of way. When I did the gear change, my wife and I had to lower our expectations for dive travel that year... man, that was a tough year! So, while I still think about a full-frame set up from time to time, I'd much rather do the trips! As soon as I notice that the 7D/Aquatica set up is holding me back in some way, and not the other way around, I'll see what the next latest and greatest for me will be... but until then, I'd much rather be sitting a gate wait to board!