I have a flashcart on the way, but it's a GBA cart and uses emulation to do GBC. So I can say that I do intend to test this out on hardware per se, it will be emulated anyway.

There are at least three different color scheme hacks for Metroid II, by the way. And yes, it would be an awesome repro cart, maybe in one of those black cases to go along with Zelda DX. Someone should really do a Megaman V DX too since Capcom backed down.