Honest answer, maybe more of an opinion.
mj, you are:
Gonna go through the better part of 200 bucks either way.
Gonna hafta run gas and wear and tear in the buggy, more dough.
Factor how the surf fishing has been the last 3-5 years.
Factor bird closures, seals, mung, etc.
Factor that you have had better luck in the boat
Factor that ya got a pissah boat, and ya catch fish when ya go out in it.....
uh, I'm think dump the dough in the boat gas tank.
I've had both the last coupla years.... for me, well, I get the bonus, (cause I'm a resident) of the Nauset Inlet side, and I live in town, (less gas back and forth) I guess I'd go with that, but, you do get more variables, (Truro, Hatches, the Race, etc.) with the seashore, pass, but you burn more gas getting back and forth...
Seashore is 30 bucks less...
If you are just looking to fish, there are so many good places to just walk on, get the night parking permit from the seashore.. heck, some of the best places, are walk on... ooops... ssshhhh....