Mike,
I don't think you will sink it but you will defo get deck wash and the rear of the board may spend a bit of time submerged but you won't sink it. Now I don't know if that bothers you or whether you prefer to sit higher in the water or bounce around like a cork not even getting yer toes wet?
Whilst out on mine just over a month ago I noticed I was sitting particularly low in the water, I thought (naively) that it was just due to the extra weight of my sodden wetsuit. When I got home I weighed myself and was disturbed to see I was 102kgs (this is heavy for me, I've since stopped eating moro gold bars and have dropped 5kgs

) I did struggle catching waves that day but that could be down to a few variables such as swell strength/direction, wind strength/direction, tides etc..
IMHO unless you are getting a cheap uber fish I would get something a little more responsive with a wee bit more volume. The PSH 9'6" WAA is 4 5/8 thick so thicker than the uber which is 4 1/4, the Starboard 9'8" Element is also thicker I believe? Or even get a custom one built then it will be perfect for you.
Hope this helps?