Quick Brushes and edge detect

Played around with the brushes in AP3 today. The Edge Detect option does not seem to work as well as LR3 beta. At times I get a small gap between the effect I am trying to apply and the edge, and at other times the effect spills over the edge into the area I want unchanged. Using the exact same photo in LR3, the brush does a very good job of adding the effect right up to the edge and not spilling over in the areas where AP3 does spill over. Maybe there is a trick that I need to learn in regards to AP3, will keep experimenting to see.

In regards to performance, I am pretty happy so far. For me, AP2 was very slow since upgrading to SL, AP3 seems to be zipping along much better, hopefully it will stay that way.