I think the projected faces look nifty. I agree that within show lighting, with all sorts of elements lit up, the fact that their faces are 'glowing' won't be so apparent.
That said, I don't think the faces work as well as the projected face on Lumiere for several reasons.
1) Lumiere is a candle, so a glowing face suits the character.
2) He is quite small, so the lack of 'depth' on the facial features is very hard to detect.
Similarly, for the cars in Radiator Springs Racers, the only projected elements are the eyes, which should be essentially flat (since it is the windshield), so the lack of depth is not jarring.