Some thought on hifloat jackets. It looks like the post , 2 posts above mine has some excellent suggestions. I was a commercial guide for years...I got an extrasport, ribbed hifloat once before a swiftwater class, and could not sell it fast enough. Sure, I popped up out of water maybe 1/2 second faster, but alot of extra flotation was above the shoulders, which does nothing once its above the water level.
The people practicing throwbagging all missed; and if I had waited for someone to rescue me, I would've been in river least 2/3 mile, cold water. AS soon as I could see a path with few rocks, I turned over and did a crawl stroke to get out of current; much more difficult with a cumbersome hi-float on.
My best idea would be to call big volume river companies (grand canyon, high water main salmon, etc.) see what they recommend; rent a h-ifloat or another rental jacket. THERE ARE SO MANY KINDS NOW. They even make a jacket that comes with extra floatation you can add/remKve.
Just while I'm n subject
O NOT BUY A RESCUE JACKET WITH ALL THE BEELLS, WHISTLE, QUICKRELEASE BELT WITH CARABEENER. tHOSE JACKETS WILLK NOT HELP YOU, AND ARE DESIGNED TO WORK WITH AT LEST ONE. OTHER PERSON WHO HAS SWIFTWATER TRAINING. I leave quickrelease belt w/ carabeener at home, if I'm not boating with another that has actual training who to use this Jacket. (There's even wa warning on jacket label, saying not to buy unless you have special swiftwater, rescue training. You can borrow, rental is the best way to go if you can find an assortment you like. Don't forget, those 25lb. floatation lifejckets are made for 250-300 lb people(and the jacket i saw with removable floatation; they may make a 'floatation belt' now, that you could cinch around waist add to a small profile lifejacket. I like to go into a store, try on options, (used sports stores as well) and if i fallin love with something, shop the net anfd getmit for1/2 the price rent one tillI find what I want, etc. All those listed above sound like excellent options to go try on....I wouldn't even put so much emphasis on 16 vs. 25 lbs floatation, unles life jacket if for exceptionally large person. I also am not aware if they PFD w/leg straps for anyone larger than kids. If your life jacket it cinched properly, it should not ever come off you, and I've never seen someone who lost their lifejacket (except on land. when they didn't hook it to something and it blew away!