I agree that extra playfields hanging around and in-the-way is an issue. But, having said that, the P3 platform is, IMHO, doing the best job at transversing this complicated(?) idea in the current age of pinball.
Heist was something like $3500 to purchase brand new. Yes, you did have to have already invested in the core *hardware*, i.e. the cabinet. Still, I think Gerry is the first one to be on track to make this whole sloppy *swappable playfields* concept a working reality.
Personally, I am hoping his vision is not too ahead of its time to work (meaning financially viable).