E4 Tech 3s here – on both bikes.
I am a big chap, and I tend to descend at a reasonable rate of knots (not due to skill, just gravitational effect). I have never had an issue with the Hopes lacking power! Love the feel of them, much more progressive than the Shimano brakes I have had (and I did like them, but these are just “better” in that I prefer the feel).
They do seem to be incredibly set-up dependent though. I had the first set fitted for me to the Whyte and they were brilliant, put them on a Stache recently and lucked out 😉 Fitted the set to my Fuel EX and never had them perfect! It’s just been in the shop for some fettling however and they seem spot on now 🙂 Going to take it for a proper test ride tomorrow (perhaps)!
I think the moral of this story is… unless you are really, really meticulous with set up (and good at it) get someone good to put them on for you 😀 I think I lack the necessary patience 😉