Not really. Normal maps baked from highpoly models have curves that are defined by gradients which are relative to the lowpoly topology. Can't get that from painting. You'll get seams. "Sculpting" with nDo2 is more useful for details in tiling textures IMHO.
if you do it cleverly you can get away with a lot of stuff. however you will not be able to manipulate the seams. unless you can find a way to calculate your lowpolies tangents into your heightmap maybe. but you can detail a lot of parts that are not going over different uv islands.