Yeah the Sub is a good board, and in 510 it'll give you a little more lower range than my 508 gave me. I think maybe consider the 2.38" - 600 MB at your weight though. The thicker one is quite a lot of board, but again that's down to your volume preferences. I find my CBD Taj which is basically the 600 2.38" MB dims works in anything chest high with some shape and a little push and up. Very smooth board and actually quite forgiving. Those are the conditions I used the Sub in so it became a bit of an overlap, and even though the Sub probably should have the advantage in those conditions, the CBD felt like the better board for the way I try to surf.
I think the Potatonator could well cover you up until you want to be on a shortboard, but it's nice to have that in between board. It wouldn't be a bad idea to leave the Sub for a minute though and then decide whether it's needed.