Well, I sure don't want to jinx myself, but thought I'd share. All die-off ceased about 10/20. Some regrowth is evident. At night I still see what look like MENs but always in the exact same spot, same individuals, unmoved. Weird. I have yet to see either radiant wrasse make any eating motion on the monti side of the tank. Not a single such movement. The other 2 wrasses aren't supposed to eat them and also show no signs.
Perhaps a fortuitous spontaneous die-off? Perhaps the radiants prefer to eat when unwatched (though that hypothesis is sure disproved every time I put in Rod's Food!).
Dunno. Worth watching....