Since I just got my MP-4S today, took a couple (yes, just two) pics to compare with MP-1B, since I'm sure many are curious.
Both pics were taken with them next to each other, with no flash on the camera, with just ceiling-mounted fluorescent tubes as lighting. And no post-processing (Photoshop) either.
Comparatively, MP-1S isn't black like MP-1B. And the light grey parts are pretty light.
It's interesting to note that MP-1S uses a different tray-insert than the other MP-Convoys (I have MP-2, but not MP-1, though I figure he's the same as MP-1B).
My MP-4S also has a weird blotch of silver paint to the right of his ab-grille... or is that intentional? Was that where Prime was stabbed by Megatron?