"sit-ins" (I wish there was a better term than this):
Pros: drier ride, some sun protection on the lower body (depending on boat), boat usually a little lighter than comparable SOT, boat can be narrower due to lower center of gravity. IF boat has bulkheads then semi-dry storage. Generally better performance than SOTs (with some notable exceptions)
Cons: safety of smaller, "recreational" sit ins with no or one bulkhead - not self rescuing, can swamp - NOT suitable for rough water. Yes you may stay "drier" than in a SOT but if the water's cold you shouldn't be out there without a wetsuit or drysuit anyway. Longer touring boats that are safe in rough water (are designed for it actually) require more advanced skills and techniques to re-enter (or learn to roll) but can use a skirt to keep most water out
Pros: Safety due to boat being one big sealed buoyancy chamber, any water than comes aboard drains back out, easier for some folks to get in and out of, easy to climb back on from the water - BEST option for a stable, recreational kayak that can handle some rough water. Great for taking kids, dogs, going fishing, etc.
Cons: wetter ride, usually wider than comparable sit-in (less performance oriented), some lacking in seating comfort, usually heavier
SOTs somehow have earned a reputation as "toy" boats or "kids" boats - but in many situations they are the preferred choice, usually because of the safety of one sealed compartment. Honestly you don't get that much wetter in a SOT than in a large cockpit, recreational sit in boat.
Cat 36 - I think the SUP 'craze' will be a flash in the pan.... another year or two and you won't hear much about them again.