I have used both dremel and the Proxxon IBS/E. The dremel is not even in the same class as the Proxxon. Almost no end play and no vibration. A well balanced tool. Very quite and more torque at slower speeds.
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I got turned on this brand by some guys at a miniature CNC milling machine forum. Dremels had to much run out to be accurate. The Proxxon uses a metal nose housing that holds two bearings on each end of the shaft. The dremel I had only had one bearing at the tip and used a plastic housing. The two bearings and the metal nose housing hold the shaft more securely in place with out hardly any run out or vibration. The vibration with cut-off disc is what kills them, sending them flying across the room. I have yet to explode a disc while cutting. The disc runs true in the cut so it never vibrates in the cut reducing jamming which explodes the disc.
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Also the speed controller on the Proxxon is very precise and can be used in low speeds without bogging down thanks to its full wave speed controller. The motor seems to try to hold the same speed no matter how hard you force the cut. I have had mine a little over a year now and love it. I also use it attached to the lathe tool post as a tool post grinder. Its seen some heavy use and still purrs like a kitten. If you can spend the extra bucks I would definetly look into the Proxxon IBS/E. It gets five stars from me.