The BLI locos seem to be OK, but a lot of people have bad-mouthed them in comparison to the Kato SD40-2s out there. There are some inaccuracies in the BLI model that the bad-mouthers are picking on; and others have picked up on it in the 'me too' vein.
As for me, I did buy a handful of the BLI models, and I do have some Kato models. I have not really put the two side-by-side to see whether the differences are noticeable or not. But, unless it sticks out like a sore thumb in MY eyes, I'm not going to worry about it. Because, in the grand scheme of things, in my little empire, those things (in this case) don't really matter to me.