Interesting tests. I'm not surprised that the difference in resolution from different backs is so minimal.
I recently tested various backs from Leaf, Sinar and Hasselblad against my trusted Leaf Aptus 65.
I really couldn't see much difference between them, they are all so bloody good that I would be happy to own any of them! If you are new to camera backs, you will have great difficulty in deciding and your decision could be made on points such as practicality, a good demo, whether you like and believe what the rep says, whether you like the software and so on, rather than the ultimate quality. I notice that reps are not bashing the competition as much as they used to, although some still do, in subtle ways. There is an increased acceptance by reps that the competition is very good, so reps score brownie points by being friendly, helpful and honest with well prepared answers that don't sound like waffle.
The needs of a still life photographer shooting tethered in the studio are different from those of a people's photographer shooting untethered under diverse light conditions, etc.
There is no way you could see the tiny, tiny differences on printed material, or offset printing, other than small variations in colour due to differing colour profiles. What's more, I didn't see any of the current backs were any better than my 5 year old Aptus 65, apart from file size, although I have to say that they were all tested at base ISO, as I'm not interested in higher ISO's. If you wanted to push me really hard for a superior file, I would probably say that in fairness, the 50MP Hasselblad multishot had the edge on certain detailed subjects, but only a tiny edge at that, something that may be of great importance to pixel peepers. But I am looking at practicality overall and as I say, once you go into print, they all become equal, although for big interpolations of files, you are naturally better off starting with a bigger file.
Much as I wanted to buy a better upgrade to minimise my tax burden, I came to the conclusion that I should stick to what I have, at least for the time being. The major difference between these backs is in the software, and how practical it is for the way you work.
My conclusion is that without a doubt, the Leaf Live View is still the best of all the ones I've seen, unquestionably, although it is still pretty poor on all medium format backs. And Live View is of major importance to me to be able to focus quickly, accurately and with certainty. Other photographers couldn't care less about Live View.
Also, to me, being able to work directly in Lightroom (via a hotfolder) is of great importance, as I prefer Lightroom to any other manufacturers software. Both Leaf and Sinar allow you to import files automatically to Lightroom via a hotfolder. I was told that Hasselblad is working on it, but no dates yet.
Edward