Eric:
I do not recommend putting any kind of brush roll in a TriStar PN except the factory replacement. TriStar PNs will squeal and rattle if they're not in good shape, with all the little nylon spacers and the felt dust seals in their correct places. My machine's PN had missing pieces and an aftermarket brush roll, and it was noisy and didn't clean as well as I expected. After putting everything back the way TriStar built it, the PN became a whole new experience, very quiet and capable of grooming the carpet extremely well.
When you get your machine, what you should do is to go to the TriStar Canada website (
www.tristarvacuumscanada.com) and download the parts diagrammes for the EX-20; they're in PDF format. You can then take your PN apart and compare what you find to the diagramme. A lot of people go into the PN to replace a belt or whatever, and they don't put everything back where it belongs; that's probably what happened to mine.
With a TriStar PN in good shape, you will not need any kind of a special brush roll, trust me. Your carpet will be fluffier than it has ever been, with no heavy grooming tracks like a lot of PNs leave.
You might like to know that I recently got a Bissell ProHeat 2X carpet cleaning machine, which is famous for pulling big wads of pet hair out of carpet. A lot of people who use a ProHeat for the first time cannot believe how much pet hair pulls up, and they complain about having to stop and pick up ginormous wads of pet hair. I have a cat, and he sheds, but I picked up almost
no hair with the ProHeat; my TriStar was not leaving hair in the carpet. It's that good, okay?
Of course, you
do have to get behind it and push! ;-)