Long-legged guy here. I have never felt that Belt Squats did much for my quads and for hamstrings there are far better exercises. The problem I've had Belt Squats, and to be fair, I've only ever used a Pit Shark, is the weight going down and back in a pendulum-like direction. This feels (for me), very similar to a low bar, hips/butt back powerlifting style squat (the way the Westside guys are taught to squat). This makes perfect if you know the history of the belt squat and how they were very popular in powerlifting gyms well before other gyms started to buy them. So for the purpose of powerlifting, they are great (getting some volume work without overtaxing the low back).
And yes, I've tried them with Olympic lifting shoes, elevated heels, reversing my body's orientation to the weight arms. I just felt that I had better options for both hams and quads to really want to use them often. In fact, I felt that elevating the heels for the Pit Shark didn't really change much of anything. However, Arsenal's Belt Squat and also the Squatmax look like they might be better than the Pit Shark that I used. Arsenal in particular (based on their unique design) looks like it might be good for quads. Again, I'm long legged and it might be a totally different story for a lifter with different anthropometrics.