If you think a human can actually perceive some sort of input lag on the Genesis' multiplexed controller input you are sorely mistaken and are spending far too much time worrying about a non-existent problem.
I don't say to perceive it. I just say that more you add, more you loose speed. There is a simple test for that. You try playing MOW on win emulator, then on linux. You will then like more to play on Linux, without knowing why. Even if it was minimal, you feel something wrong. Everybody know this about wifi console sticks, so why would it be different on the Neo-Geo and Sega consoles?
I know i prefer the Neo, and why would i prefer it, sometimes games are the same for example on Sega Saturn, or on PS4? it's because of that. You can't quantify it, but you know something wrong, and in an arcade connection type it's better.
It's just simple logic. Neo-Geo is a fast interface, with a bios. Saturn is a slow interface, and is based on the megadrive.
It's the same when in alpha 3 console version you can change commands to long, arcade or normal. There is a difference, and if you play an arcade stick, you feel better with arcade commands, even if you doesn't know why.
I remarked this when I was playing with various kinds of adapters on PC, and changing OS'es.