I don\'t have the SI brushes, but I have some of their other kits and they are very good. I have the wizoosounds brush kit and it\'s very good for the money ($9.29). It\'s 24 bit, has four velocity layers, and has some nice snare drags. The SI kits are pretty reasonable, as well ($23.95). I think I\'ll have to get these, myself. My experience has been that the SI drums have better ambience and a rich sound. The wizoo drums have more velocity layers, but ound a little sterile without processing. HTH
You can just go to their site, buy and download them. http://sonicimplants.com/
The demo sounds great.
I have the wizoo kit and it good at a slightly lower price. This SI one looks well worth having.