I tried it in my '03 450 early on, and took it from a 50wt to a mid 40 in just over two hours, so one of them would be me. My own samples of MCF have stayed in grade as long as 11 hours, although normally, I would never run it that long. People including members on this board have submitted UOA's here, to me personally, and elsewhere. No one has to believe any study if they choose not to; they, or you, can test your own oil.
Who are these "others" who have compared them? Can you point to a published paper?
Whether YL full syn was ever any good or not is now a moot point, because it isn't the same oil anymore. It's a new product, and we can all either wait and see, or test some ourselves, or ignore the whole thing. From my standpoint, whereas I had evidence that the old product was inferior, the new product is an unknown value, so my own opinion has moved from distrust to skepticism.
As far as my feathers being ruffled, don't imagine that it means that much to me. I have an affordable, convenient, highly effective oil to use, and I know it's one of the best available because I researched the question. It's really not important to me whether it's the best there is or not, and I'm not looking to replace it.