I see your point what your saying I think is a more 3D effect to character...
for bizz cards thought the simpler (less colours etc) the better Generally speaking
details can get lost in production and costs may increase with more colours etc (but new technologies may have negated this in printing production) (thats what you have to balence out and build in to you profit margin..all your out goings)
but for sign-age I defiantly would be going down this road of a more complex 3D effect and take it further with the whole image..
but I like your thinking and yes, were you going with it it works for me a great suggestion you can't see it but its there and does add to the effect..at a sublime level and that were it counts a lot of the time to catch the eye