Steve Fisher recently used something similar when filming The Grand Inga Project. He had to use the device when sucked into a whirlpool at one point. They also had some kind of breathing apparatus in their vests(10-15 breaths). Having one without the other didn't seem like a good idea. Granted the size of the water features there are unusual, but wearing such devices IMO would be to run beyond a river's normal flow. Obviously, it is edited, but he didn't seem to happy with its performance after the swim.
This might ruffle some feathers
, but... get a Creature Craft if you wanna strap an inflatable to yourself. You will run way crazier stuff in a CC than you would ever dream of in a round boat with a CO2 auto-inflating thingy.