I had both the A7r and the A7s; I returned them both, each for different reasons. The A7r had shutter vibrations that affect focus stacking, and the A7s, although good in low-light, 12mpx was just too small. Since I have three video cameras, all with 10-bit Pro Res or 4K, I just did not find it that useful.
The A7R II looks very good indeed, with one question mark for me.. The 11+7 bit lossy file format does not sound like it will match what we have in the Nikon D810, and for me these things count. For me the 64 ISO and functional LiveView of the Nikon D810 make it the best camera I have ever used, so far.