I'd only make one last point: Nobody's decided that high performance aircraft will do 1,500' circuits. It's just a CAAP....
I'm not sure why you are so sceptical about this. Every high performance aircraft I come across will fly the circuit at 1500' AGL. I'm not sure what part of the country you fly in, but in my neck of the woods you get anything from kingairs to 737s in the circuit, and they are at 1500 AGL.
On a side note, if there is a high performance aircraft in the circuit, you probably wouldn't being over flying the field anyway, because: a) they wouldn't want an aircraft overflying them only 500' above as this may cause a TCAS advisory and b) there's no need to overfly as you will know what the duty runway is based on the aircraft already in the circuit so you can just join behind the other aircraft
