I did some re-tiling in my bathroom and after much deliberation, decided to get the Fein MM to remove the old grout. It worked like a charm. I did pretty much destroy the carbide blade by the time I was done, but it took no time at all. I was surprised and disappointed to find out that I can't cut tile (4 in. sq. ceramic) with it-even if I use a diamond blade. At least the company does not recommend it.
My next project with it was to sand the railings and posts on my porch so I could re-paint. I used the finger sander to get in between the posts. I found that the heat did cause the velcro on the pad which holds the sandpaper to actually melt and fall apart. Not only that, but the pad itself became unglued from the metal base that attaches to the tool.
After a little experimenting, I attached the pad back onto the metal with a good two part epoxy for metals and I replaced the velcro holding the paper on with adhesive-backed industrial strength velcro. Worked like a charm.
I love my Fein MM. Patience is a virtue both in having good results and saving the attachments from damage.