The A7R has such flexible files you can do whatever you want with them, plus you have wonderful resolution when you need it. Unless you are shooting video a lot or shoot black cats in coal cellars at night, the A7S is perhaps not the best choice IMHO. The regular A7 is the often overlooked great all rounder.
As an experienced B&W wet printer, I feel very confident saying that the beauty of B&W lies in the subtleties. Understanding tonal relationships is key. It is not about tones in the absolute sense, but how they interact with each other within a given image and in relation to paper white/mountboard/lighting that will take a traditional or digital printer to the next level. The difference between a 'digital looking an in your face B&W image' and a beautiful one that leaves you agape can surprise you in its subtlety. Sadly, there are no easy shortcuts to mastering this.
Rather than consider different cameras, I would spend as much time as you possibly can looking at beautiful prints to understand those relationships. Years ago I chose to work with the master printer Robin Bell, in London. Seeing his prints, from my negatives, transformed my own printing. Now, whenever I get the chance, I spend time around beautiful prints - you can even learn a lot from the very best book reproductions.
Many current photographers with no history in B&W darkroom work produce nasty images IMHO, because they have little interaction with the end product: prints! If you can afford it, I would select some of your very best B&W images and then sit down with a talented printer and work towards the best possible prints. You'll learn more in a day than five years looking at images on computer screens. As expensive as it may seem, it will also save you a fortune in scrap images going forwards. If you don't want to spend lots of time processing images, but are happy to spend the money on prints, getting your files 'close' then using a superb printer (person) to make the final product makes a lot of sense.
