If you get a multimaster you may find that you use it much more as a cutting tool then a sander, I bought mine for sanding when the current model first came out; however, today I almost always use it for cutting. It can often do the job of a jig saw or sawzaw, in a small area, quicker and safer. Sanding is still good too, and has a plethora of applications
The Fein Multimaster, began its life as a caulking/sealant cutter--back a long before the current design Then the caulking cutter version got more power and became a different tool. Someone came up with the triangle sander idea, and the "detail sander" or "delta sander" became the corner sander of choice.
Along the way cutters and scrappers were introduced, and then the true strength has come to be in precision cutting, and it still sands well. If you reaaalllllyyyy need cutting/scraping power than you can get the Fein Super Cut... it costs a little bit more. The new Multimaster (not yet available) is 250 watts, with a quick release --I really want one of those.
Many here have commented that the Festool is a better "sander" and that would not surprise me. The osculating action of the Fein means that the center of the sanding pad isn't moving, not so with the Festool. Although the dust extraction of the Fein does work, it's an add on; whereas, the Festool's dust extraction is built in.
I can't image NOT having a Multimaster, it's one of the best tools ever invented (now being joined by the domino) but for sanding, I would go for the Festool.
Fred