This Rotary Tool by iFixit vs. Dremel comparison please?

It not the tool you need but the bit tool. Get a diamond cut off disk like one of these: http://www.amazon.com/s/?ie=UTF8&keyword...

As to the rotary tool part, if you do not have one it becomes a matter of how much it's going to be used, how versatile you need it to be and how many hours a day it may be used. Personally I went with a dental lab Emesco jack rabbit with a short arm like this one: http://www.ebay.com/itm/Vintage-Emesco-N...

This machine with a good dental lab hand piece can be used for hours a day without the vibrations a Dremel gives you. But it uses 3/32" dental bits high quality rather than the larger cheaper Dremel bits.