Switches and Cords
For final sanding procedures like leveling a floor repair or sanding a countertop, it's handy to lower the sander's speed because it's less likely to gouge the work. All of the sanders in the group have variable-speed dials, which I like, except the Hitachi; it only has a high-and-low speed switch, which makes it more limited. The Bosch, Craftsman, Makita, and Ryobi have dials that are easy to reach when the machine is running. The DeWalt's dial is tough to reach; it's on the handle so you must move your hand to get at it. Porter-Cable's and Hitachi's speed switches are a difficult reach, too.
As for cords, when will tool companies realize we want them long? The Makita has a 16-foot cord?kudos. The others are 6 to 9 feet long, which is too short for my liking.
Belt Release and Tracking
Belt Release. The metal belt-release lever on the Makita is notably easy to use. By contrast, the thin metal lever on the Hitachi is painfully sharp. I have doubts about the durability of the plastic release levers on the Craftsman, DeWalt, Porter-Cable, and Ryobi tools. While they all work as intended, they feel stiff and seem like they could snap off. The Bosch lever is particularly stiff.
Tracking and Adjustment. Tracking is the tendency of the belt to stay centered and not wander off the rollers, as happens on some old belt sanders I have. Once in a while, as the belt wears, you might need to tweak the tracking to keep the belt centered. Also, you must reset the tracking for each new belt.
All of the belts tracked steadily once adjusted, but some of the adjustments were easier than others. On the Porter-Cable and Hitachi models, the thread pitch on the adjustment screw is too coarse, which means a small turn of the knob moves the belt too much. The rest of the tools have finer threads, so more turning is required to achieve the same result; however, you have more control and don't find yourself twisting the knob back and forth repeatedly to get the adjustment where you want it. I found that the coarser adjustments on the Porter-Cable and Hitachi, actually make it more cumbersome to adjust belt tracking precisely.
Power and Finish Quality
Platen and Finish Quality. To ensure a flat finish, a sander's platen should be flat. I checked the transverse flatness of the platens with a straight edge and found most of them to be flat or slightly convex. The DeWalt, Bosch, and Makita tools are closest to perfect; the Craftsman, Hitachi, Porter-Cable, and Ryobi also are very close to flat. The Bosch unit has a composite rather than metal platen and only the Ryobi and Craftsman lack a cork or rubber backing pad under their platens. Interestingly, I didn't detect much difference in finish quality between any of the sanders when surfacing glued-up cherry; all of them left an impressive finish here and throughout the test. Bosch, DeWalt, and Makita sell optional sanding frames for their sanders. The frames (which fit around the base of the sanders) make it much easier to achieve a really flat finish and prevent gouging on large surfaces such as countertops and floors.
Yaw. None of the sanders in this group yawed or wandered, as some older models I've used do. They all run straight and true, even when I ran them one-handed. This is particularly evident when sanding to a scribe line. The Bosch, Craftsman, and Ryobi were easiest to keep on a line. I found that their handle locations (at the far ends of the tool) allow for better control. The Makita and Hitachi also were very steady working to a line.
Power. While I wouldn't call any of these tools underpowered, the Hitachi, Porter-Cable, and Makita definitely have extra grunt and would be my choices for heavy stock removal, hogging off paint, or knocking down a hard finish. The Craftsman, DeWalt, and Ryobi models, on the other hand, feel a bit strained when pushed hard, but were still capable.