Having used the A7r2 for the past two years I personally believe a lot of the negatives are over emphasized internet forum hype. I've never had trouble with my batteries. Yes I change them throughout the day but I and the talent also need a break as well and I've used the camera on many filming projects where we've been filming for many hours straight. Having dual card slots, maybe nice but another internet over hype. It wasn't too long ago I was shooting assignments with only 36 frames of film before I needed to reload. Seems like an added element that could create a mixup.
I will say the improved AF would be nice, however I am a firm believer not to buy any electronics, computers, etc.. for at least three months after it's been released. It does seem like we are beta testers for everything anymore.
The one reason I still would choose the A7r2 over the a73 is because personally when shooting talent, portraits, and lifestyle I am always finding the need to crop / change the reach of the lens via using the in-body super 35 crop. I had to use the A7S over the summer, you could not crop with it - it was a pain.