Think you need to work on perfecting your skills more. Don't stagnate. How about light-dependent outlines that don't need outer AA then? Do it as good as you can and then sure, return to outer AA if it's a style you like. Colors can be brought together much more, creating a palette that can be applicable in any otherwise seemingly single color segment of the sprite.
Captain America doesn't slouch, he has a huge square jaw and looks valiantly in the face of adversity. The dither on his suit is good because that's the sort of texture he has going on with the scales, but it needs to be done more, I think. Knees too low, arm muscles tweaked, illumination on shield and numerous little edits all over the place. Hope I helped.
