You'll find a strict distinction between "Whitewater" enthusiast's boats and the craft you're talking about. I've got a couple of true whitewater rated boats- Sotar and Maravia.... and I've also got a Watermaster that I use for fishing floats. Is the Watermaster capable of use in whitewater? Sure- within reason, of course. I've had it down true class III water without any problems. The big difference that a lot of folks who are strict whitewater enthusiasts often miss is the weight difference. The glued on pin style is (usually) fine on extremely light weight, minimally loaded boats. Backpack boats. The weak link is usually the oars that come on these set-ups. I upgraded my Watermaster's aluminum oars to a set I built out of two carbon shaft kayak paddles. Wasn't hard to do. If you overload one of these things and then pull like crazy to make a move around or into a wave, you could bend the oars quite easily... or tear the glued mount from the tube. Whitewater people are used to making hard, heavy pulls on their oars- and those boats are meant to accept that load without any problems. Apply that approach to one of these boats and you're looking for problems. Just yourself, a day cooler and some fishing gear? You should be fine right up to class III water- A side benefit of my Watermaster is that my legs dangle like a keel- it's damned hard to flip the thing for that reason. What it does NOT do well is punch thru holes. You will get hung up in these little boats in bigger water. In that case I plunge my legs as far down into the flow of the wave as possible- and the pressure on my feet pulls me thru.
As a side note- there are a lot of newer, larger designs out there that use these oar attachment points. I WOULD NOT RECOMMEND anything that's supposed to carry two people using this system. That's a bad design choice in my opinion- Dave Scadden has recently pushed these things to an unreasonable level in my mind. They weren't meant to handle a lot of weight for the long haul. If you're considering one of those boats, do your homework. Lots of bad blood about those boats and that company. The new Outcast designs and the Watermaster should serve you well if you stick to the limits I referred to. Those two brands are well made and well respected by folks who know boats.