Paul, I do fret work mostly, and I hardly ever have to do any amount of sanding. What I do is, I use the ultra scroll reverse blades to do the cuttings, I got them from Mike. After cutting out the subject, and depending on the frailness. I'll either remove the paper pattern before sanding, but, if the object is frail or, delicate, I'll leave the pattern on the wood while I sand it on the opposing side. I do this for the strength of the paper and the glue. Of course, this means that when your cutting out the pattern, it is good side down. Next I'll either sand or remove the pattern, depending on the frailness of it, you be the judge. I'll then do the sanding, and all I use to do most of my sanding is a detail sander. One of those types that use sanding pads that looks similar to a stretched triangle. Sometimes, I will lay an old towel under the object before sanding it. Like before you be the judge of how delicate the object is, and if you need a soft layer to protect what it is you cut out. I swear, I've never lost a cutting to sanding anything this way, and, I have often wondered why other people didn't sand their work this way. Presently, I'm using a no brand name detail sander, and I use 220 grit pads. Sanding this way is a lot like other things we attempt to do, it does take a bit of practicing. You will have to learn how much pressure to use, so you don't break something. And, it's good to learn what type of cutting should have the towel placed under it before sanding, not all pieces need the towel, but some do. I learned to do my finish sanding this way over the years, simply because I hated sanding my work by hand. Try this, it might solve your sanding troubles. I don't know how this will work if you use spiral blades, I only cut with flat blades. Ooops, I forgot to mention, I even use this method when sanding thin delicate fretwork ornaments, they are the ones that need the towel under them when sanding. Sorry for being so long winded, but, I had to be to get all of the info included.
Len
P.S. I have no experience with the sanders your talking about, I have looked at them, but didn't buy any.