I really don't like the plates under the heels for any kind of squat. I know I would fucking crash and burn doing that, and I am sure there are other just like me. :-) If I ever see anyone doing it at my gym, I let them know that it could be a safety hazard if the plate slips. Most of them have no idea that the plates could shift.
This wasn't at the gym, but I officially got one upped by the two bros working at GNC. I was buying some pre-workout and a guy from my gym was there. We were talking and he asked me about my last meet. Once I mentioned the 644 squat, then it was time to one up me big time. The two bros behind the counter started talking about how they squat or squatted back in high school. The bigger guy (who was probably 6'2, 275) said that he had a 1500 total on the squat, bench and hang clean. I think he said he hang cleaned 275. He also said he squatted 700 really deep. That means he also benched 525. Then the smaller guy, who was probably 160# max had to one up the other bro. He said that he squats 800 deep and benched 5 something. I told him he should compete, since he pretty much would hold all the world records. I think that made them think about what they were saying.
Today in the gym I saw a high school senior benching 365 for sets of 5, fast, flat back, with almost no leg drive at all.