As it were, another user, Luxx-71, just recommended some different aoe talents to try, in this post Looking for updated BM M+/raid macro - #10 by Luxx-71, I ran a quick test on the trial dummies and it does seem to perform about 5-7% better than what I have posted. Ill give it a go in keys and update as appropriate but you can give that a shot if you are keen.
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Update: In keys, the performance improvement seems to evaporate. I ran 4 darkheart 20’s today (darn ring still didnt drop), with my talents I got one end of dungeon final parse at 202k and one at 205k, with these talents I got one parse at 188k and one at 195k. Very close, but I will continue with my original talents (The Wowhead M+ talents, posted above or pulled from wowhead) for the time being.
Or the variation could just be the standard ups and downs between dungeons/groups.
Leaving this here for posterity.