Matt,

I actually did some white water kayaking when I was younger and about 5 years ago I played for several days in the surf on a Hobie sit-on-top kayak (there was no wind). I found the difference to be rather big. Maybe your sit-on-top is a newer improved version but the one I had then wasn't to great in wave riding and I found it to be pretty unstable in the surf and hard to do recoveries on. I've used a plain polyethyleen (rotomolded) closed kayak a lot and that one was very easy to surf and control. Inuit rolls were a breeze in that kayak.

Personally I would love to have a kayak again for those storm days that we seem to have more often over here. I found it to be a nice addition to having a sailboat.

Wouter