There are 2 things to considers: Price of camera and price of housing.
For the price of camera, the GH5 definitely is a winner.
If Nauticam doesn't make housing for the GX10, you are only left with Gates, which have very expensive and bulky housing.
Also, 150Mb for 60fps 4K seems very small for file size, so will have to see how good is the image after all the compression. Other than that, GX10 do have lots of flexibility in term of WA and Macro, and built in ND filter. I'm just curious how much control can you have on the camcorder once it's put into housing. Many modern camcorder have touch screen menu now so once put into housing, you can only use one or 2 buttons.