the power pegs rock fore and aft 20 degrees and have adjustable tension (i had to tighten'em up a little) its not all that crazy once you get used to it.the motion is very natural and you kinda become one with the bike. i was concerned about jumping, but after trying a few small jumps it makes your foot plant better (especially if you land off camber) instead of the peg jerking your foot to it, the peg comes to you if that makes any sense! it really makes the attack position way more comfortable. i'm genuinely impressed by them. as far as stressing ankles or knees more,once i stopped fighting with them and let them do they're thing it felt less stressful on the joints. foot placement seems more critical but once i found the sweet spot(its right where it should be, just in front of the heel) it was go go gadget; power pegs
the only drawback is they're about twice as heavy as the stock ones,but i figure that weights down low and it might even counter balance some of the top heaviness!