I've never been able to dump out the excess water of a submerged sit-in kayak and re-enter it in deep water.
I have always had to drag the thing to shore or to really shallow water to do that. One time it was a 300-yard swim halfway across Lake Lanier by Two Mile Creek Park, with me towing my sunken vessel with my 15 foot poly rope clipped with a D-ring to the waistband of my swim trunks. That was a lot of work.
Well that just sealed the deal for me. Sit on top for the win.