I agree that this is a better stage, but actually think it is more than incremental. The Stage 4 is a completely new interface based on the Wave 2. This Layer approach I think opens the door to additional flexibility in the future. It has the same Arp as the Wave 2 (polyphonic, gate, pattern mode, etc), effects per layer, layer switch feature, support for the P5 unison features and a 73 keybed that a lot of users wanted. I am hoping this may lead someday to a six-layer instrument where each layer can access any engine, piano, organ, or synth.
-dj