Well, I've been using my Dust Deputy for a while now. For the last few weeks been using it on a daily basis to vacuum out my pellet stove every morning before I light it up for the day. I don't think you can find a finer dust around the house than that.
Since I know a few of you had been wondering how it performs with fine dust, here you go.
The filter had a good amount of very fine stuff clogging the filter, but there was actually very little dust in the shop vac bucket. The Homer bucket was actually pretty heavy with dust. I'd call it 2.5 - 3 gallons of ash.
So, in my book, it did pretty well, and lasted much longer than if I had vacuumed out the stove without it. Saved me a few filter cleanings, that's for sure.