I’ve purchased and used both for several years; mostly DIY and residential demo cleanup. I first purchased the basic DD kit with the bucket before the UDD became available; I attached it to a Fein vac and used it for a year or so with non Festool tools and for clean-up tasks before I started purchasing Festools. When I purchased a CT26 I used the basic DD in conjunction with it whenever cleaning up heavy debris or a high volume of sawdust/wood chips. Eventually I purchased the UDD only because it clamped the CT26. In my experience both perform the same, but the UDD is more convenient when used in conjunction with a Festool dust extractor that is moved around a lot. So I’d advise asking yourself if the added convenience is worth the extra cost to you. The UDD adds considerable weight to the CT26, especially when it gets above half full, so it takes a little more effort to move it around. My home, shop and yard has several floor grade changes of 6-8 inches that I have to lower or lift the UDD/CT26 over as I move it around. I usually use the handles on the UDD bin to lift or lower the CT26, but this caused the original plastic hose garage to break due to the imprecise attachment/sloppy interface between the hose garage and the UDD dust bin. I replaced the busted garage with the redesigned T-loc garage; this improved things, but the fit is still a little sloppy. If you rarely lift or lower your vac unit this is an irrelevant issue. I’m happy with the performance. Also the higher vac hose connection point makes it more convenient to use the extractor with saws, sanders and dominos if you don’t use the boom arm; I find the hose is easier to keep off the floor and less snagging occurs. Annoyances: don’t like the tapered connection Where the vac hose attaches to the cyclone, the hose frequently falls off if pulled too hard (tape can solve this); the inside face of the dust bin becomes heavily caked with very fine dust, so that partially defeats the advantages of “contained dust disposal” offered by the plastic bag. I find I have to wear a dust mask, carefully remove the dust bin cover and gently brush off the caked on dust into the bag before removing the bag for disposal - do this outside; the fine dust still diffuses in the air!
