I have used the h20 audio set up for the past 5 or so years.. It works well and I have never had water get my ipod wet. Headphones last me 3/4 of a year and I just buy new ones when the old ones break... I put the ipod in the front pocket of my lifejacket so I can turn it on and off easily. I cover the headphones with a skull cap as I ware a skull cap every day i kayak...
As far as when to use them I have to say that the numbers at 3200 cfs with tunes is even better than the numbers at 3200cfs... I dont use them too much on creeks but I guess if you are solo who cares if you have headphones on.
For me front surfin the BV park alone at dusk with tunes is one of the best parts about kayakin..
"I feel better than any other time when I am in the mountains and uh I cant explain it ya know...." - Shawn Farmer..........