Knee sleeves allow me to squat more, but not because of stored elastic energy. I wear them a size down and they help a lot with my knee pain. I put them on before warming up with the bar and I can already tell how springy I am out of the bottom. Without the sleeves on, I'm not as springy because my knee aches cause me to slow down a lot when I'm nearing parallel. It's apprehension due to anticipation of pain.
The reason I put them on before warming up is because they're really tight, and the slightest bit of sweat and leg swelling from warm-ups would make them that much harder to put on. By that point, I'd need KotJ to come lube up my legs and powder me up everywhere else.
They're approved. Here's the approved list: http://www.powerlifting-ipf.com/file...17-07-2017.pdf
I cannot read this entire thing. Sleeves help a little mechanically but they boost confidence because the knees feel better.
I have a pair of rehbands and two pairs of titans(one yellow jacket set. ) I prefer the rehbands for day to day training and save the titans for actual heavy work and competition.