My experience with the Wave 2: It’s super versatile and usable. IMO the architecture with the four layers is fantastic because you can do a lot of things with it. I have some super fat sounds using layers, as well as some patches with multiple split points and 3-4 different synth sounds, which is great for live playing with my band.
Also the Wave 2 is indeed usable as a “stage piano”, although the sample library does lack some important sounds (e.g. organs are basically non-existant, probably because the Nord Stage and Electro have dedicated organ modules). Obviously you can load your own samples, so this is not a huge deal, but it’s not a 100% “out of the box” experience.
Regarding the keyboard: It is very high quality and allows for very expressive playing, also for piano sounds. Originally being a pianist and only then a synthesist I must say that for piano sounds I still prefer a weighted keyboard. I wouldn’t say that always playing one type of keybaord completely ruins the other, it will just take some getting used to if you were to switch (that’s why I prefer to have both types of keyboard around, but obviously that may not be an option…)