I have used a DA sander and a belt sander as well as a 5" disc sander on bars in the past. The disc sander is far too aggressive if you want to preserve any etching. The DA sander works O.K. but takes a lot of time and effort to achieve acceptable results. If you want a highly polished bar, the DA sander working from 80 to 120 to 220 grit does a fine job, but be prepared to spend an hour or two and lots of sanding discs. The belt sander works pretty quickly but you have to be very careful or any etching will be lost.
The HF Surface Preparation tool is a huge timesaver and yet does not seem to be so aggressive that threatens delicate details. I do often use a disc sander on the edges first if there are any significant burrs as the surface prep tool does not knock them down, and the sharp edges can be hard on the scotch brite type drums.
Mark