I have also seen here in the US people convert the Trinity machine (which is for commercial carpet cleaning) into a duster. It has a duster head attachment for the orbital head and I've seen some comments about how they like converting a machine they already use into a duster when needed.
Some of us old school operations use upright Sanitaire commercial vac with a duster head (remove the brush and replace with a concave metal bar) - the idea is to vibrate/shake the soil out from the back. The Badger was too aggressive for us at our shop, we have a lot of older rugs. But I did like the improvement of the smaller version - the Cub (we call it the Baby Badger). I've used it at a few events, I like it has less weight to it, though it's still very loud.
At the ICE Expo Tom at Centrum Force had his duster tumbler, and this is like a big cage that slowly turns and dusts multiple rugs at once and the soil falls out to the bottom. This by far has been the best idea I've seen in a long time in dusting, in that you don't have to monitor it, and you can go do other things. I don't know the price point (I'm sure it's high) and it may not be the right idea for any other than large rug plants.
Sometimes for the price... getting a vacuum and a part time student worker, may be the best bang for the buck. =)
By the way, I have not been on here for ages... and I want to thank Clean It Up for not forgetting about me and sending me a nice email sharing what I have been missing lately.
Lisa