I think the real issue for circles is for techniques that put the hook deep in the fish's anatomy. I don't believe fly fishing is in that category. In my opinion, only the crab fly falls into that category for striper fly fishing. Trout - no issue; steelhead/salmon - no; freshwater bass - doubtful; bonefish - nada; etc.
Chunk bait is in tht category because the bait is sliced into easy to swallow pieces, then laid down on the table with the rod in a holder (rarely in the hands). Eels fall into that category because most people wait for the bass to get the weinerschnitzel down the gullet before setting the hook.
The circle hook is a set line hook. Long liners use them because they can't tend to the fish until they circle back around, and circle hooks put the hook in the lips for them. But these same commercials don't use circle hooks on their jigs and hoochies because they hook in the lips anyway. Bait fishing is an individualized set line. Circle hooks really apply there. I'd like to see the regulations require circle hooks for bait fishing.
I went away from crab flies last year because of the deep hookings I had the previous year. Stripers put their crusher plates (throat) on crabs right away and you get no time to set before the fly is too deep. Further experiments with circle crabs will continue next year on monomoy.