Quoted from nephasth:
I thought it was just a quick swap of playfields, didn't know some components would have to be swapped over too.
They don't. The PF's come complete. (to my knowledge at least)
The swap-out feature is so you don't have to disassemble slings, flippers and pops to take the mech out of the game for service. They just unscrew from the underside and drop thru the PF.