obxsabresfan,
Sandshark is a good detector. I got mine used and it has served me well. New price is good value and there are very good values to be found on used Sand Sharks if you look a little.
I use the 10.5 inch coil nearly all the time. That coil flips up with the moderate to strong water movement. It needs a coil brace. I don't like coil braces since I like to change the coil angle when moving from wet sand to water and back to wet sand as I change my sweep. 8 inch coil does not catch as much water; but I stay with the 10.5 inch coil and put up with the flipping.
Sand Shark handles the black sand of the Outer Banks well. It will find good targets at good depth, balances well (can swing it easily all day), is sturdy and has a great warranty / factory support.
I have not used the Garrett or White's PI's but do have a little time on a Headhunter Pulse and like it a lot. I have not gotten to the Outer Banks with it yet.
For a non-PI detector in the wet sand and water, when the sand gets black, I tend to like a CZ over an Excal. Factor into that opinion that I have a lot of time on a CZ and not a lot of time on an Excal and may be running a little too high with sensitivity on the Excal since I get a lot of nulls on black sand concentrations.
What ever way you go, best advice I have is to spend enough time with any detector you get to go through at least a couple sets of batteries. You need to listening to the detector, change settings over different sand conditions, and learn it's particular language. The more time you spend with any detector makes you better at detecting with that detector than you are likely to be with any other detector that is new and different to you.
Cheers,
tvr