"...please keep it to facts and related information"
Good advice, John.
I have the Shopsmith DC with the fabric bag on top and the collector bag on bottom. I've never been happy with it collecting dust or particles from the lathe. Maybe the problem is the 2-1/2" collection hose. Maybe it is the motor strength. And maybe it is the CFM of the whole combination.
What I'm building now is a multi-purpose air filter/circulator/collector.
I got the idea based on one that I saw in the shop of our club's president. It is basically a box on casters that contains a furnace blower and 3 stacked filters (general purpose, dust, and Filtrete). His had a "periscope" build onto it with a 6" high by 20" wide opening at lathe height. I was very impressed with how well it drew dust in from the lathe even when it was sitting about 20" away. My DC can't do that gould when it is 6" away.
So I'm building the base of mine as one unit, but varying the collector configurations. There will be a similar "periscope" for the lathe. Removing that and exposing the full face of the filters will allow it to function as a shop air filter/circulator. A short "stack" collector will provide the basis for a mated down-draft sanding table. You just wheel it in place, lock it in position and turn it on.
I've got the bottom, top, and sides of the basic blower/filter box cut with dados for assembly. I also have the wiring harness and switch controls assembled (low, medium, and "hold on to your tools"). I have to pick up some more plywood for the endpiece and stack. With that, I'll have 2 of the configurations done and only the sanding table to work on over time.
I'll submit pics when I have it complete.