No. I'll just re-note that 3DCoat seems to be able to more accurately represent your bump and displacement painting. Photoshop and AMPaint will show grayscale imagery.
If you are comfortable with mentally interpreting grayscale, should not be a problem.
If I'm modifying a decal (after roughing things in using A:M Paint, saving the decal and opening that decal in another paint program with the affected model open in A:M with the decal applied), saving it, then updating the view of the model in A:M as I go along, wouldn't that get rid of mentally interpreting grayscale? The model should show the changes made to the decal as far as I know...of course I would have to re-save the decal and update the view in A:M after each change, so it wouldn't be realtime.
I may be wrong, but it makes sense in my head.