I have gear stowed in my PFD pockets like other do here. I have a rain suit/hat/gloves/hammock first aid kit, in day pack that sits in front of me as I paddle. I lash my packs in, but keep day pack handy in case I go over and wind/waves separate me from canoe.

The day pack will float and I figure IF I go over, I can grab hold and use it as a extra flotation device and make for shore.

After reading his account, I'm wondering what if anything he could of done different/better in the way of keeping hi survival gear closer, even in the situation he found himself in?

I don't paddle rivers/white water, so maybe I'm all wrong about this idea, but here's my thought's on it.

I think I would get a waterproof wet water type back, the kind that rolls down and secures with buckles. I would have all my ditch gear in that , that won't carry practically on my person. I'd have a short floating type line attached to bag, and hooked via carabiner to the D-ring on my PFD.
I have a small rescue knife on PFD that I could use IF bag became entangled and I had to cut myself free.

I know in raging waters the bag might make it harder to swim free, but IF you could make it okay to shore, you'd be far better equipped for survival with maybe a decent tarp/hammock/sleeping bag type rescue blanket/rain suit/ signal mirror/ mini-flare gun and some of those boater type floating smoke flares. A magnesium type fire starter/folding saw/hatchet and maybe a pistol/ pistol grip shotgun might not hurt either.

I'm sure there are drawbacks, but curious about what others think. Every time I read a story like that, I think what I would do in the same situation and how I would avoid his miscues. Of course hindsight is always 20-20, but X-Mas is coming up and you can never be to well equipped in a emergency ;)