I can’t find any real tests being done on it. Well, other than on MiSTer. Tested pretty extensively on that, but I find these numbers are often totally different than the same controllers on a PC.
Lon Seidman did a test, but his tests suck. LOL
Cheers 
I was just going to suggest the MiSTer spreadsheet. When have you seen different numbers? As I understand it, the MiSTer sheet will give you the raw PCB response time but won’t include all of the Win10/driver/polling/etc. overhead, so maybe that’s what’s causing the discrepancy?
Mostly with the Dualshock 4 numbers. There was another but I forget which. On PC the DS4 is faster wireless than wired. Reversed in the MiSTer chart. Even overclocked/wired/PC the DS4 is still slightly slower than over BT… but is more consistent.
I remember now. The 8bitdo DIY SNES kit seems really laggy on the MiSTer lag chart. I’ve never seen another real test of them, but I have seen a guy do a no death run of Ninja Gaiden with one (BT on OG hardware). Seems like that would be hard to do with a 0% chance of input on first frame.