Andrew Liszewski just posted his review of 8BitDo’s DIY kit. Overall, it’s exactly as to be expected: https://gizmodo.com/it-really-was-easy-to-make-my-old-snes-controller-wirel-1828523571
My only opinion on this is that I’d feel strange replacing the guts of my original SNES controller with this. I’m sure most classic console lovers like myself would preserve the original board, should we ever decide to put it back to stock, but it’s still not something I think I’d do.
…but it seems like the perfect mod for new SNES Classic controllers!!!