IP and Sandman have given you excellent answers. I will add that it was a little confusing when you said that you would like to use the machine for "prospecting", since that term is normally associated with nuggets in their natural state, not coin/jewelry hunting. So I'm assuming (seeing as how you're on coastal CA, and you're also referencing "surf") that you are not asking for a unit that can do both natural nuggets, and crossover to beach/jewelry, right?
With that said, a pulse will far-&-away go "deeper" and "be more sensitive" (to answer your questions). But as was cited, you will pay a price of having no ability to discern iron. Well .... some would argue that you can tell nails/iron somewhat by tone (ie.; double vs single beeps, etc...). But even those who have become proficient at such tone guessing, will no doubt dig quite a bunch of them "just to make sure", as nagging doubts will always have you wondering

And things like bent nails (verses straight ones) can fool you. And I wonder if an elongated gold item (stretched out chain, or gold stick pin, etc...) might not mimick the tone of a straight nail? It's a guessing and odds game that does indeed pan out for those who are proficient with them. But no doubt, you will see them leave for "greener grounds" (beaches with less nails), if storm erosion has left the beach riddled in some nail rich areas (around burned down piers, places with lots of beach bonfires, etc....)
And as long as we're not talking about tinsel thin earing studs or whatever, the excaliber can get pretty darn deep when you put it in all-metal mode (when conditions allow). So for example, I bet for a standard class ring or gold band, the pulse and the excaliber would be at about the same depth anyhow, once you put the excal into all metal (which gets an inch or so deeper than disc.). So if you were in an area where that last umph of depth really mattered, then you can still simply get it by going to all-metal, and being on par with the depth of the pulse anyhow (unless, as I say, we were talking about tinsel thin chains or something, in which case the pulse would get them, while a standard coin machine wouldn't hear it).
Another factor is mineralization. There are some beaches where you simply have no choice but to use a pulse, even if there were lots of nails. If the beaches where you want to hunt are gunpowder grey in color, then maybe they'll be too mineralized for the excaliber?
In my area, our beaches had a lot of industrial/commercial history (wharves, shipping, fishing, etc.....), and are less "touristy" (except for a few) than your "baywatch" style of beaches in So. CA. So when we get good storm erosion, there can be way to many nails on our beaches to use a pulse. It's all just in taste and the conditions of your beaches, your goals, etc....