Unless it sinks real fast it will still be carried out of sight,most rivers Ive ever seen are moving pretty good and as a result you cant see the bottom too good,why not just tether it to yourself, or put it in one of those gps water proof pouches with some closed cell foam.I do that wit my 76 when I am in the saltchuck kayaking,just to keep the salt off it and I still tether it to me.
AMEN the way I see it if you wanted it to float you should have bought the 76. The 76csx and 60csx are identical in performance. The only difference is the obvious one is just water-proof and the other Floats. I bought the 60csx for the same reason above I really dont want to chase it much rather bend over and pick it up. I suggest if your fear is losing it then a good lanyard and carabiner.