In the North East we have several of the top motor builders in the US all running together on a weekly basis. The difference between motors worked on by tuners adn those that you can buy from the unnamed OE manufacturer are big. I'm biased, but even with racing against some of the best in the biz motor wise, I've never wanted for anything rip wise since I started running for Kwik this year.
Also, Shawn, the main motor dude is an electrical engineer. His guiding priciples for motor building are grounded in science and testing. I still can't get over his dedication and his commitment to a scientific approach in the quest for rip.
BTW. I don't know when the last time I changed my brushes was. A quick skim every once and awhile and some cleaning of the brushes are all you need.