Actually Jack, the Oreck brushroll, in my experience, is pretty excellent. The Oreck has so little suction so the brushroll has to make up for that and it does pick up surface little pretty effectively. Don't be mistaken though, I still don't like Oreck lol.
As for the 2 pics above, you can clearly see that the Dyson uses very short and sparsely spaced bristles - the Kirby uses longer, thicker and very dense bristles. Like I said, any fool can clearly see which brushroll is going to have better deep cleaning action and better grooming of deeper pile carpet. With all Dysons statistics and impressive use of ever-changing technology, a half decent brushroll seems to have missed them completely. I've seen carpet sweepers that could groom a carpet more than that lol.