See, I kinda like that contrast, with a normal looking dude gradually becoming more ridiculous as the game goes on.
*Whips out candy cane rocket launcher
"It's business time motherfuckers!"
Here are a few more variations. #3 is one I had made already, I was thinking of making him an unlockable character called Bram (Brother fRom Another Mother)
I like 8 the most, but still think you should add more contrast to the nose and remove the dithering because, if the screenshots you showed a page back are full resolution, the sprite is so small on-screen that it's hard to distinguish the nose and notice the 1-pixel dithering you used for the clothes.
The visible eyes and exposed hair could lead to richer animations, and I think giving him no mouth is okay, since you have so little space left for it that it'd probably make the sprite harder to read. Still, you could try that out as well.
@Ashodin: I think that wouldn't work, since the sprite has 4x4 glasses (with the inner glass being 2x2). That's too small of a space to fit cracks in and make them easily recognizable.