I haven´t ever sampled Scotch Brains or Datils, but i´ve eaten hundreds of Fataliis and i think a lot of this stuff is a matter of perception. If I had to, I could somewhat convincingly argue that yellow chinense of a given heat level all basically taste pretty much the same, and i believe that to be the truth, if you´re of a certain mindstate where you prefer to explore similarities. However, i could also argue that, even if the existing differences between these varieties may be small, they´re also significant and worthy of note. And, again, i believe that to be true and it is, in fact, the reason why i grow and eat multiple types of arguably similar chiles.
I think that the secret to understanding chile flavor profiles and, possibly, ALL of the finer things in life is to become adept at exploring both the similarities and the differences between different examples of the stuff we´re into. The ol´ ¨compare and contrast¨ schtick from primary school....