Hi Andy, I just saw your post to me in SLOG - I don't get notices when someone replies,...I have to manually check it seems. Anyway, I think Bill has answered your question.... basically the side wall refection is the total issue regarding any perceived imaging difference between 45 and 90 degree dispersion. Theory is (and I won't do a great job explaining this quickly) is that the sound coming off the panels travels 'straight' (perpendicular) off the membrane as it is functioning as a line source. Also all wavelengths that are shorter than the width of the panel are traveling 'beaming' out from the panel (which is why the flat cells are arranged to appear as a curve and which achieves the degree angle of dispersion) (of course lower frequencies do not beam, but the imagining has much to do with mid and higher frequencies than lower) So....when you sit in the middle listening position that means that a lot of sound energy is flying past either above your ears or below your ears and a lot is traveling past your left side and right (not actually direct to your ears) ... it's a bit over-simplified of course, but only sound that goes 'into' your ear is what you hear.... having more energy with 45 degree dispersion directed to you increases (I think) the SPL or volume, but the imagining is more related to how much the sound is interacting with other parts of your room - if the room is very wide and there is no chance for side wall reflection (like first order reflection) then it's 'ok' and fills a large room naturally... but not so much if the room is narrow ... of course room treatment etc. can all change and support this one way or another... and to remember the back wave and how you treat that is also very critical - keeping in mind there is a virtual convergence behind the speaker - be it 45 or 90 degrees and depending on what you do with that changes a lot of things too.... (standing 3 ~4 feet behind the speaker to experience that is very useful and interesting!) I hope I made sense to you. Of course all the other changes to performance after PX panels introduced and then the first application of distributed resonance and then to use bass focus arrangement also added a lot of performance improvements!