I hope you don't mind me chiming in here. I recently had the opportunity to use the first RECSEA BMPCC housing earlier this year in the Philippines. I just got around to releasing my video clip:
I have a fairly extensive write-up on the vimeo page about the housing if anyone is interested. I'd be happy to answer any questions here as well.
It was really the first time working with Prores/CinemaDNG files for me. I've primarily been a dSLR shooter (on land), but having the latitude that the BMPCC provides in such a small package was really the big selling point to getting the camera in the water.
In regards to support, I primarily used a Joby Focus with the Ballhead X. For me, this was a extremely versatile item. 3 points of contacted worked for me easily, and when I didn't need the support, I would invert two of the legs upwards, which would work as side grips, which would allow me to keep my rig smaller by not having to add additional grips.