I used my 705 with the 9 inch LF coil on it several times and it works great in the dry sand, and very well in the wet. There is some falsing, but targets definitely ring out. Target ID is not as accurate in the wet sand and several deep quarters bounced around into the low range of numbers. Nickels ranged even lower into the 2-5 range. Hence the reason I mostly used all metal mode.
I did not venture into the suds or water since I don't like getting that close with a non-waterproof unit. Been there done that and almost lost several different units that way. Never know when a big wave or big splash will swamp the unit so I don't take the chance any more.
I used it in all metal mode as well as pattern 1 but some good targets ( ie, not iron) broke up a bit in pattern 1 so I kept it in all metal for the most part. Could not use it in Prospecting mode due to too much feedback from the salt water. Ran it at sensitivity 20-22 range, ground balanced it auto without the beach mode. It ran very smooth in regular GB mode so I did not try to re-ground in beach mode.
I would imagine the LF coils will work better than the HF coils in the wet, salt sand. I did not try my MF coil yet but will in the future. I like how the LF coil acts in the wet sand and how it can sniff out silver and coppers in the dry, so that is why I continue to use that exclusively at the moment.
Will try to post more updates as well as some pics in the future on further expeditions with the 705 at the beach. I mostly always use my CZ6a and E-Trac there, but it seems the 705 can hold its own and since it's light, has tone options and can be customized via the coils and other options the unit has, I think it's a winner.
As we all know its a single frequency unit, so the multi frequency units will do better in the wet sand, but if I want to gold hunt in the dry (put on a HF coil), or search for old silver and copper coins among the nails in the dry (put on the LF coil), the 705 is more than capable of that task.