Ive tied thousands of these flies. If you have any questions on tying with them feel free to hit me up.
There is a little learning curve to tying them but once you get it down it only adds a few seconds to each pattern. I do really well on them but also do well on other nymphs.
This would be the way I would describe legs on nymphs:
Lively Legz: great for the profile of the nymph, no added movement
Rubber legs/crazy legs: some added profile, but added movement
soft hackle: not much for profile, but a lot of movement.
I haven't tested lively legz against soft hackle, but compared to standard nymphs I saw a 3:1 pick up on a LL pheasant tail vs a Standard pheasant tail. I fished them tandem, and alternated the location of the nymph to be sure they weren't just hitting the anchor fly.
They work well, but somedays the fish are keying in more on soft hackles, and other types of patterns. But I have tie and caught piles of fish with LL and will attest that they are worth it to have a few in your box.