I think that it would be great if a manufacturer makes a housing considering the use of the built in flash, but before I get critized for this comment, I would like to mention why :
a) underwater digital housings for DSLR are very expensive, so unless you got big bucks or do this for a living, is very hard to justify spending so much money on a housing + domes + flash etc. so I think that if someone but the housing and "started" using the camera and it had this feature, I am sure that it would help for some photographic situations. I know , an external flash would do a better job, but I think that this flash is better than NO flash !!!.
In order to control de flashes wirelessly, the flash itself has to be up, in the ready position, you can control it so that you can turn off the camera flash but still talk to the other flashes.
How about if you price this housing for $799 with dome for 18-70mm??
So, what are you waiting for? make the housing to include usage of the built in flash !!! if this has been discussed before sorry for posting or if a manufacturer has come up with this already pardon my ignorance !!
your comments are appreciated.