I have the DTS-400, which is the same sander with a different shaped pad.
I only recently bought the DTS and it has far and away become my favorite for finishing. I'm looking to get an RTS for the pad shape (but later, like when I have a paycheck... [mad])
The dust collection is very very good. With the Rotex, I always have the vacuum on hi. With the DTS, I have to adjust the suction or the sander sticks to the material. It's as dust-free as you can get. This afternoon I was sanding a stick to be used as a divider in a shop drawer and when I sanded the end-grain by holding it against the pad, I was impressed to see the dust scoot across the pad into a dust extractor hole.
Now, I will say that there's a thread on exchanging the pads on a DTS-400 and RTS-400 as the main sander is the same. yadda yadda, the end result was that you could on previous models, but not the current models for some reason. Regardless, the thread concluded with a rumor that this year there will be a new sander that is a DTS/RTS with easily exchanged pads. If you aren't in a hurry for it and the rumor pans out, that may better for you. Personally, I'm holding out on an RTS for this new version then eBay the DTS.