raw video can definitely be more useful, if you know how to handle it. keep in mind, that raw video will need lots of space, so you'd need a ssd/external recorder, if you want to record longer videos. (and lots and lots or hard disk space for storage).
most cheap raw cameras don't offer much in terms of handling. while it's pretty great to get a black magic pocket cinema cam for $475, you'll probably need an external battery, ssd-recorder, ssd, some nice 16mm glass or a speedboster adapter to get a wider FOV with dslr-lenses, an external audio recorder, if you want audio, and a rig to put it all together. that's at least another $2000. i don't know, if there's even an underwater housing, that would be usable with that. also, no zoom & manual focus.