I've got the Rotozip, and it is a great tool for so many things. I'm a Professional Handyman (35 years now) and I use it a lot. For cabinet fitting, drywall, cutting holes for ceiling lights etc. One customer wanted new baseboards through the house. No problem... ahhh the 1/2" tile was installed after the original baseboards. I used the Rotozip with the "Zipmate"attachment and cut them off at the tile line. Didn't damage one piece of tile. Also I like the flex shaft that they have for it.
I thought it was cool when it came out. Just after getting out of the service I hung rock for a few years and we would chuck an 1/8" drill bit in a trim router body and use that to cut out openings for electrical boxes and doors and windows. So I'm pretty sure that it ws a drywaller that came up with the rotozip!
Anyway it's a great tool for what it was designed to do!