Hi Lee,
2360's are big fun aren't they. I still like mine a lot. How much EQ Re you putting to them? I found that over the long run they sound most natural with the JBL CD compensation curve or something close to that.
When it comes to drivers and diaphragms, in my opinion, the 2446 or a 2450 with the ribbed Ti diaphragm sound the best when running without tweeters. It's not clean HF energy but its there but it's there. A real 2441 sounds worse and Be diaphragms even worse as they require more and more EQ on top. By about 12kHz the big drivers are operating under the electrical and physical constraints of an 18dB low pass filter. It's the Ribbed Ti diaphragm ringing on, superimposed on the clean output that is responsible for the extra output up high.
As for the harshness way down low, I don't think it has much to do with the amount of air moving in the diffraction slot as it is the amount of air moving in the front cavity, between the diaphragm and phase plug. 194dB is about the limit that air can be modulated without gross distortion, that is quite easily achieved in the airspace in the front cavity operating at a 10 to 1 compression ratio, especially at low frequencies where the diaphragm motion is large.
Anyway I hope you have fun with them!
All the best,
Barry.