Sam Hurd is one of the best photographers currently out there in my opinion. He's been shooting with the A7r for a few months, and just put up a review of the A7S. He is using primarily leica lenses, and mentions the usefulness of focus peaking in the viewfinder with manual lenses. Its a good read from a different perspective!
http://www.samhurdphotography.com/2014/gear-reviews/sony-a7s-review-sony-a7s-vs-a7r