I got so fed up with BAs that did not suit me that I made my own ... the Mk2 was excellent.
As a coach and White Water paddler I wanted lots of pockets for quick access to notebooks, bits of tat, rescue kit etc, plus adjustability to fit over winter clothing, drysuit etc as well as summer-wear (next to nothing in bulk) ... and bits of kit to keep me comfy and safe while my mates shot off downstream trying to catch my canoe after I blew it on a big rapid...ie 1st Aid and a brew kit...
It is all well and good having a clean and slick BA and all the safety gear in your boat but if and when you get a real trashing and your boat and all your kit is disappearing down the gorge to the Falls of Doom and you are sitting bashed, battered and bemused on a little beach then having the basics on your person counts for a lot...
Bill Mason used to reckon that one of the benefits of having a Cedar canoe was that you could use it's shattered remains as firewood to dry your kit and yourself before the long walk home after a bad trashing ...
I ended up with 3 patch front pockets - shaped and sized so as not to interfere with getting back into my boat after a merry little swim - 2 flat internal, zipped pockets, a strobe patch and two pockets on the back, the lower one accessible from the side. All the pockets were mesh for instant draining...
The adjustment was with side straps and shoulder staps with clean ends - so the tape could pull through if it got snagged and thereby not end up holding me underwater for longer than I can hold my breath.
One rescue knife (fixed blade) was on my left shoulder ready to be grabbed with either hand and a back up (one hand opening folder) was in a pocket. All the pocket kit - including knives - was on lanyards so that if the velcro fastening burst open I would not lose anything. And yes - I would prefer to be trapped on a trashing stopper with the razor sharp knife open and whirling around me if I drop it .... I might get a few nasty, even life threatening, cuts as I try to recover the blade... but at least I still have the chance of recovering the knife to cut the rope I am snagged in that is holding me in the water longer than I can hold my breath... I would rather trust my buddies 1st Aid skills than drown.
I went for a superior buoyancy (never did calculate the Newtons - but it was a lot more than commercial BAs) so that I would float high, and fitted quick release (and snag release) leg loops as well as a waist belt ... so that the BA sat well and I would not slide out if someone tried dragging my senseless body out of a rapid..
There was a bit more foam in the front to increase the odds that I floated face up... heavier items (such as hydration bags) were carried in the back pockets...
The buoyancy Aid was comfortable to wear and never got in the way on, in or under the water or on the bank during rescues.
Manufacturing cost precluded going commercial with my design...