There's hundreds of dollars differance in the MSRP. Most purchases of these machines never put enough time in whichever choice they made, to benefit from it's capabilities, so if your an occasional hunter, go with the less expensive BHID.
That said, I would choose the BHID. Minelab's a sponsor to this forum so I won't discuss what I think about the Excal, except, it's in the top two for the worst swinging water machine made(above water or wading).
Save yourself about $275 +/- with the BHID and you'll have one of the top two best swinging water machines(above water or wading). It also comes with a extra years warranty over the Excal., transferable to unlimited owners. Battery life in beyond belief and you can use inexpensive Kmart specials as well as rechargeable NMH's. I don't wish battery replacement for an Ecal on my worst enemy. The BHID is only rated to 25ft. submersable depth(99.99999% of water machines are ever used, deeper than that)and the Excal is rated to 200ft. or more(?)
I've never hunted Fla's beaches, but what I've read on the more popular forums, they have low mineralization. This might lead to more choices than you've listed in your question. Hopefully some Fla. hunters will chime in.
Neither machine has a "finds gold chains" reputation, but both are good on rings, with the Excal getting better depth, if that is important to your style of hunting.
Whatever machine you buy, learn it's talk and walk it's walk, and go find some of that Fla. gold.