You're correct.. It is a cautionary tale.. But more as well, considering thread title..
Freshly scrubbed beach: Unless the immediate area is the site of a known treasure ship wreck (or old on-shore gathering point for caching / divvying riches / spoils), any 'treasures' will be modern day (and if not a past or present gathering point for sun bathers, probably not even that..)
Without the lure of possible historical treasure being present, there really is no reason, to me at least, for the presence of expensive not-totally-waterproof not-balanced for salt deep-seeking detectors.. Even if that treasure ship / gathering point possibility exists, the need for deep-seeking equipment only marginally improves recovery odds under described conditions, since, unlike inland gold, where nuggets at even moderate depth are stationary for all intent and purpose, the bulk of post-erosive shore finds will be discovered at the toe or in the face of sand 'cliffs', in one of the three gathering zones parallel to the shore line and shallow in run-out cuts..
There is no doubt I have nowhere near the shore time invested in multiple worldwide locations as you do, Steve; I can speak only from what I've observed along FL's Atlantic coast.. However, based on these observations I find absolutely no valid reasons for bringing a 7K as currently mfg'd to a salt water coast.. It simply isn't necessary.. All I can forsee is detector problems up the road.. All risk; no reward..
Swamp