Thxtheater ... your speakers responses look very good but the sub has a deep notch at 100Hz that is limiting its high frequency response to 80Hz, I believe ARC could gives a value of 110 - 120Hz if that notch is reduced.
I would also give my music config a listen first before lowering its xover points. You'd like the sub to handle the lower frequencies for it produces them easily with minimal distortion. Though your mains go down to 20Hz, i guarantee you their distortion at 20Hz is much higher than the same 20Hz produced from a subwoofer. That's what subs are designed to do ...produce low distortion sounds at low frequencies and at high spls.
At 75dB your mains go down to 20Hz and below as shown in the charts. But what about at 100dB or more where movie peaks are recorded? Their FR curve could show a response down to 50Hz or higher and with much more distortion to boot! Hence the need to allow the sub to handle the low end.
Thanks for your feedback and a question: Is ARC smoothly correcting that 100Hz notch in the "after" curve? I think it's hard to see with the screen shots that I ran ARC. With the sub, it looks to me like the green line is almost perfectly hugging the ideal target curve. I defer to you all on what you may be seeing.
Since you brought up the issue of the sub, I was wondering about the rolloff since my side surounds are being crossed over much higher than all the other speakers.
One thing that I have wondered (and I'm sure it's been answered somewhere somehow) is why ARC rolls off the low end and why in terms of the measurements does every single graph I've seen fall off at the upper end at around 10-20kHz. The beryllium tweeter in the Revels extends far beyond 20 without distortion. Is this a function of the speakers not being pointed straight on towards the microphone? My assumption is that the HF will be most impacted with a rolloff in those cases.