Well hopefully, given time, developers will actually get FPS games to work on Wii. Now I can't say that games like Red Steel don't work because I've never played it but looking at the reviews it seems like they haven't got the control scheme right. It's a dissapointment as I thought that Wii would be perfect for FPS games.
I like your idea and it sounds like it would work. I hope that Metroid will nail the controls.