Well, I have used the tool. But it only works with box selections. I'm talking about Lasso Selections. AFAIK, GIMP has a similar feature called "Grow"...
I deal with huge amounts of pictures everyday, and export from PDN and then importing in GIMP is a huge pain. I also don't want to learn GIMP from the ground up because I appreciate PDN's versatility more, and with the amazing plugins hosted by the community, GIMP really lags behind.