"FULL SET VS. WIFI-SAFE
The Full Codeset takes advantage of all that Project M has to offer. However, for WiFi and replays to function properly, the WiFi-Safe set must be used. The WiFi-Safe set does not differentiate between L/R lightpress and full press or have C-stick buffering, nor does it have Stock Control or Stage Strike. The PMBR recommends you play with the Full Codeset unless you're specifically using WiFi/Replays. You may switch between these two builds simply by replacing RSBE01.gct, the menu2 folder, and the system folder."
From the Project M website.