I shoot a Canon 7DII and Nauticam. I'd really like to have a TTL trigger that solves the problem of using the onboard strobe as a trigger because of the awful recharge delay after a few frames with the onboard strobe.
I purchased the UW Techincs model and used it for a week, and discovered that after the first shot you have to wait 2-3 seconds before the next shot or you get a greatly diminished strobe output (dark, useless image). To me that is no better, in the long run, than the delay with the onboard strobe. I sent it back and the shop checked with the manufacturer (I had hoped I received a defective unit) that this is a normal condition for this device.
The Turtle version doesn't seem to have the Canon problem solved either.