Even on a 4-channel controller, I’d rather have two actual extra controllers (like the Denon SC-2000s or even midi mediaplayers). Forget to press the deck change button (or in a hurry not FULLY pressing it) and suddenly you are backspinning your playing track. Funny looks guaranteed (just smile – spread your arms and take a bow!).
My MC6000 had 4-channels and deck change, but I hardly ever used it. Like Terry said, if you know you’ll be playing something like Happy Birthday but are waiting for the signal, you cue that track up in both deck 3 and 4 and you can always start it in seconds 😛 .
.
