I am in my vacuum store every other month, grab about 7 belts (they are cheap). We are using the Sanitaires front and back, but mostly on the back. We use the QuickKleens, the narrow ones (the wider ones do not vibrate as much). We do not have the brushes in them, and we use a concave VGI brush, the brushes replaced with metal inserts - this is a rug beater head.
I think the other dusting machines are fine, some a bit too aggressive in my opinion, but this just works for us. Of course we are getting rugs in regularly so we do not have the impacted soil problem that many do.
It's kind of a non-issue though - ANY dusting is better than no dusting at all… but claims that heavy dusting gets 98+% of the dirt out are simply untrue. If the soil is greasy, if the rug has ever been surface cleaned, it won't matter how much you beat the damn thing - it's not coming out until you wash that puppy and scrub it out.
Lisa