In the above photo I used the Definition slider (by brushing the effect in) of Aperture 3 to enhance the wooden wall of the barn, and I think the result is really wonderful. Textures pop up nicely and give extra punch for the barn. I found the Definition adjustment very good and much better than Clarity adjustment in LR3 (not totally sure though if they adjust exactly the same thing).
This Aperture vs. Lightroom pondering is really taking some time from the main thing – photographing. I want to have a decision soon.