Well, if the activator was that good, you'd find them in the industry trade on carpets, but hate to say it SEBO rule the roost with their stiff bristles and not forgetting they do make a delicate brush roller incase you have thinner types or precious underlay. Their brush rolls however do not spin at the highest rpm, so its no wonder the industry love them. Carpets are groomed and cleaned well with SEBO brush rolls, yet they are also protected by them as there do not have beaters on them. Same with Oreck.
Jamie, you pose a good question on why the activator has been recommended by carpet brands. Possibly because Hoover paid these companies for the use of the carpet brand's name and in tow, the company would recommend Hoover for their activators? Hoover have been known to do this before with other companies as well as rather off-set ideas like British Allergy Foundation approved vacuums, on ones that are bagless cyclonics -yet we all know that bagless is far from hygienic when it comes the time to empty - and where is the BAF seal approval then??
I was looking through a lot of my old Hoover brochures of late. The Turbopower 2 and 3 series blurbs have to be seen to be believed - Hoover claim that the tools offer 180% more suction than using the previous vacuums Hoover sold, which kind of mocks the Senior, Junior et al before the TP2 and 3's came around.
One has to take things with a pinch of salt. For collectors, the difference is that we may well care for our carpets because of the range of models and brands we choose to collect. However to most buyers, if a Dyson seems to be the most technological brand around, they'll more than likely buy it regardless of the brush roll type.