Angle grinders run at circa 10,000 to 12,000 rpm. Rotozips and similar run as fast as 30,000 rpm.
We stock the M14 Vacuum Brazed Core bits, they are designed to be run at 10,000 to 12,000 rpm.
Rotozip is possibly the worst bit of kit i have ever purchased,, absulute pants., sold it on ebay .
Grinders , good blades, core bits and drills are the way, no doubt .
I also have the bosch grinder with the hole cutter attachments , thats a good piece of kit , do you do the core bits what attach to these grinders alan ???