Hey Bob, I have not used the dust deputy for dust collectors, But I recently got a dust deputy for my shop vac. I am surprised at how well it works! I cleaned the canister and filter of the shop vac, and have used it for about a week now. The five gallon bucket of the D.D. is now half full of fine sanding dust. There is nothing in the canister of the shop vac and very little on the filter!
I do have a home made chip separator in front of my dust collector. It consists of a 30 gallon fiber drum with a steel lid. I used plumbing fittings to mount the hoses to the lid. Here is a kit of fitting to do the same thing:http://www.ptreeusa.com/dusthose.htm.
This system works very well. I do a lot or re-sawing and planing, and I only have to clean the dust collector bags about once a year. I dump the barrel about twice a month.