Can't say that I've tried this twisted hackle technique...Seems to me, though, that it would be worth a shot on nymphs rather than emegers. Most I've seen have a beard style soft hackle. Which, IMSHO, would be a more realistic impression of the legs...
In answer to Louis' last question: My favorite emerger pattern is the one they're biting on. Not trying to be a smartass, really. My "emergers" are the traditional wets that I carry. But, when things are going fast and furious during a hatch caught with a dry on the end of my tippet and all I'm gettin' are bulges with no hits, I simply nip back the wings and hackles, put a dab of mud on the fly, then get back to business.
However, back in the early 80s when these things were just becoming the rage and I got the Supplement II for my
Index of Orvis Fly Patterns, I used this pattern:
Note that Orvis forgot to include the beard style hackle (Wood Duck) in the recipe.
After a couple of seasons in not seeing any difference in my catch ratios, I stopped using 'em. FWIW.
Dano