Here is the difference between Mayflash and Official adapters.
First of all the polling difference from the Adapter to the Gamecube controllers.
- Mayflash polls at 125Hz
- Official Adapters poll at 833-1000Hz (depending what port and how many controllers are plugged in).
From the adapter to the USB port they are identical, they both poll at 125Hz. However, it is worth noting that because the USB Polls are not synced with the adapter polls, a Wii U poll can be up 1-1.2ms old, meanwhile a Mayflash can be up to 8ms old! (thats nearly half a frame).
Both of the adapter can be overclocked to 1000 Hz with custom firmware that will help aid the above issue.
Mayflash will disable the 5v line unless you have both USBs plugged in. The Official adapter will send the 5v line regardless but disable the rumble bit (within the GCC protocol) until the second 5v line is plugged in. (You can hack the Mayflash to enable rumble AND 5v over one USB but you have to be careful about the amount of power you draw. Find the tutorial on this by clicking here).
They function identically regarding values, in Wii U mode.
Mayflash also has an additional mode called PC mode where it allows to controller to be a D-input device and it polls the controller at 250Hz (on update V04, update V05 now polls at 125Hz).
Here are pictures of the polling rates on a logic analyzer.
Official Wii U (1 poll every 1.2ms):
Mayflash Adapter (1 poll every 8ms):
Mayflash Adapter, PC Mode (1 poll every 4ms):
