When i tried the clone megadrive pads(the 6 button pads), it ran well, but only acted as one button joystick. I couldn't get the second button to work in snow bros, but with another megadrive pad(ascii megapad) it works. Maybe it's thing of the game, but i recall that happened the same on another games.
Cammy, are the 2 buttons working ok with your pads? on all games?. seems like i will have to give it another go when i have time.