@cebix I've now had the opportunity to open a few 8bitdo controllers up now from different lines. It honestly appears to me that the boards are identical between old a new models of the same type. For example, I switched the buttons and board from one of the older SF30s into one of my new SN30s and it was an exact match. When I swapped them around the only difference was the sticker and slight difference in grey color. I'm pretty sure the difference is just cosmetic and the stock firmware.
I have read that there were changes to the wireless radio, but you would need somebody with more specialized knowledge than me to verify that.