I finally took a look at Crane's proposal in action - I quite like it to be honest. It's pretty much the clothes greyscaled, but the lemming otherwise appearing as normal. Only one color to worry about, that's good.
Yeah, I prefer this over my original color scheme. Unless there's strong objections or a competing proposal that's either similarly effective or really popular, I think I'll use Crane's proposal going forward. I might tweak the exact color a bit - I'll look at this closer another time - but the general idea, and the rough color, I mean.
EDIT: Integrated in commit b89aed4, and will be included in the next RC build update. Note that this doesn't mean the subject is closed yet - further discussion is still open and it may change again before the stable release.