All in all, I personally find these enough to call it an upgrade. For me the sound without headphones was the major limitation of the 700 series so an improvement on that end is good (especially on lower end models). Also the GrandTouch-S might be more usable now. The weight of 875 keys might still be on the very heavy side though...
I would appreciate a soundboard as the CA901 but it remains to be heard how the new system compares. I will wait for some more reviews before I commit to any of these, but since the quality control of the Kawai CA line is problematic, the CLP800 Yamaha series is for me the way forward.