You are right but IMHO at the moment there are other most important drawbacks for underwater use:
I saw some really incredible land footage. It's a tool that in the proper hands can deliver amazing results but I think that at the moment it's better suited in a controlled environment (studio set) than as a run&gun tool.
The screen is at least two generations behind the mainstream manufacturers in terms of contrast and brightness. It is also physically extremely soft. In fifteen years of using, testing and working with digital cameras on all six continents and in extreme conditions I have never scratched a rear LCD. Yet somehow I managed to scratch a big hole in the BMPCC's LCD screen on the first day or field use. I have no idea how, but I now have a group of about a dozen bright yellow pixels engraved permanently at the top left of my screen
Camera arrived with one visible hot pixel, and also a large dust booger on the sensor. The dust was easily removed with a blower, but the hot pixel is there forever unless Black Magic comes up with a sensor refresh mode, which many camera makers offer.
There is no in-camera card formatting, no file erase, no thumbnail review. More importantly, there is no indication of the amount of time left on the card. Camera can not remember the last aperture used when the lens is changed or the camera restarted.
Autofocus is, to put it politely, a work in progress. It doesn't work with all lenses. Indeed it seems to only work with a few lenses, and when it does work with these lenses it does so in a slow and inconsistent manner. Pressing the Focus button puts a white square on the center of the screen and the lens then starts to slowly autofocus. Maybe.
I'll be gentle. The audio in the BMPCC sucks. Problem is not just the tiny in-camera mic, but the audio pre-amps as well.