The Sea Hunter II actually does have a bit of discriminate available (there are y-tube videos on how well or not, it works), and that is unusual for any P.I. detector. The problem is, as you can see in one of the demo vids, that it isn't very effective, and you lose depth if turned on. That defeats the purpose of using a P.I., IMO.
I have and use both a Sea Hunter II, and a CZ-20 (same detector as it's replacement CZ-21 except the pinpoint button has been changed from a push button, to a touch-sensitive capacitance type). At popular resort beaches, the PI will drive you crazy with all the trash you're going to recover, and I can tell you, when you are recovering trash in waist to chest deep ocean, you will be worn out before noon.
I MUCH prefer my CZ-20 for wet to in-water beaches. You will still have to recover a lot of targets that fall into that gray area of "pull-tab gold", unless you're happy just finding coins.
The Ex-cal is an excellent machine, but you still have to deal with questionable targets. I also think it is a bit more problematic. I have a friend who keeps two of them, since one always seems to be back for service, re fine wire strands in the cables, that break, and issues with leaks. He loves the detector, but also has told me that when Minelab does a repair, IF you want it warranted against leaks after you get it back, you need to pay a (significantly higher fee for that).
I've never owned an Excal, so no personal experience there. I have a Sovereign for dry sand hunts, which is the same detector circuitry but in a control that is not waterproof.