As boring as it may sound discussing vacuum cleaners i invested quite a bit of dosh in to a Numatic, which are commercial side of the Henry type vacuums. They've got a slightly wider hose for gobbling up more cack, and i bought a 6m long one so that the vacuum doesn't need to be dragged around behind you everywhere, a reusable bag and some decent filters.
I can't remember the model i think it was the 570 on this link, basically it's got two Henry motors in it, so it's a beast!!!
A good vacuum is worth it's weight in gold, no more sweeping and kicking up dust, it takes seconds to tidy up the work site and the customers actually think you are a god for being tidy.
Here's a link for the chap i used in Brum, i had a wonderfully dull yet strangely fascinating conversation with him about vacuums!!!!
The Numatic NVQ and NVDQ Quiet Vacuum Cleaner Range for noise sensitive areas
It's not small, but i use it all the time.