First ... I'd like to ask you about your goals.
It sounds to me like you are after fine filtration and a reduction in the amount of dust you'll be breathing in. If that's the case, I don't feel either of those machines have enough power on their own to pull the fine stuff outta the air to begin with. Everything you add to the system will only make that problem bigger. The ratings on these things are very very unrealistic - figure less than half what the spec sheet can pull, when new, with a 100% clean bag. After a few minutes of sanding, your bag is clogged and that performance drops even further. If you add devices to help with separation, they will take a toll on the airflow as well.
If your lungs really are that important, buy a respirator and wear it while making the sawdust (and well after you've stopped, too) until you can save up enough cabbage to put together a more effective DC solution.
Despite what seems like a simple thing, cleaning the air in a wood shop takes quite a bit. It's not cheap. Not by a long shot. A far less expensive solution to save your lungs would be a respirator.
Now, if you're just looking to avoid sweeping up as much, either of these will undoubtedly improve that front. They won't do as well as a full system, of course. In this case, though, I would look at filter area in addition to the particle size filtered. The more area of filtration, the longer it takes to clog up the bag and reduce performance. I don't really like these horizontal dealies much because they make adding a canister filter more trouble. A canister, in so far as footprint, will offer the most filter area by far.
A respirator in addition to one of these will be a pretty good start ... but if you're looking to avoid wearing that respirator you either have to spend some $$, stop woodworking, or settle for less protection, I'm afraid.