The SUP I used was definitely in a completely different league (at least for me) than a kayak or rowboat. But too, I've been kayaking/rowing for years, so I'm good at it. I only used the SUP for a few days.

The one I used most was the NRS model that is the shortest and most sporty (so leaning toward wave catching and surfing, more than straight line). But then it still felt more "loggy" than whitewater kayaks on flatwater, and they are also optimized for something else (turns). Anyway, that's all subjective and there are no numbers, so I would like to try both a "non inflatable" SUP and a different inflatable SUP. I can't imagine actually using a non-inflatable on the "big" boat, because of the bulk and "banging around" factors, but just to compare the various types.

The magic was in the "just hop on" platform, the standing up (also made seeing into clear water neat - almost like snorkeling when the water was glassy), and the great view while paddling around with my eyes 5-6' off the water (vs. being low in a kayak, or low and facing aft in a rowboat) . Oh and in being able to just "land" anywhere (because I could pick up the SUP and carry it ashore so easily). And of course the exercise value was just enhanced by the inefficiency