I got a chance to take my new 7dMKII to Raja Ampat a bit over a week ago. Overall very impressed. Autofocus and general useability, especially with the nauticam housing, are great. Didn't shoot much above 1600 ISO, but overall tended to feel that as long as exposed well I'd be reasonably happy with up to ISO 3200 if necessary (and very happy with ISO 1600). By ISO 6400 Noise/detail loss started feeling quite problematic. Haven't had a chance to do much processing of them, but I just threw a few ISO 3200 shots and two iso 6400 shots onto flickr(lightroom processed) with the raws in dropbox if you want to play with them yourself (shots chosen for ISO range/exposure, not composition/quality).
Note that the one wide angle 6400 ISO shot was using a magic filter but is beyond the range that lightroom is willing to let you adjust tint.