I have about 1.5 years of use with this tool, and quite honestly I am sure I have abused it about as much as possible, and I keep waiting for it to not work one day, and I am still waiting. Most of the abuse is due to using it for tasks its not really made for, as I continue to grow my tool collection, I would always find myself needing to do something for which I didn't have the best tool for the job, and it has ended up being called upon to cut off, grind, sharpen, engrave, etc far beyond what I am sure it was meant to do. I have used tungsten bits and had them catch, bounce, etc like when enlarging a hole in metal, but the hole isn't adequately larger than the bit so you end up playing surgeon, and the bit catches and rattles around the hole-tool comes to complete stop-then starts spinning back up! I have done similar stuff with cut-off wheels and grinding stones. Needless to say this has skipped and bounced around many work-pieces and has had the chuck/mandrel hit edges when trying to get into a spot that is too tight. Yet the tool still works! Now I will say it seems the speed switch is less adjustable than it was new, seems I can turn the wheel and rather than get a nice smooth increase in speed, I get stepped increases. Also when turning the speed way down to the minimum, if it torques out, it won't have the power to get moving again without a small bump of the speed selector. I have also more than a few times accidentally depressed the lock button while in use, which makes for a nasty sound. Anyway, I am pretty impressed that it still functions near perfectly, and wouldn't hesitate to buy again.
The things that could be improved....somehow,,,, would be that chuck locking button, as it is positioned great for easy use, but has occasionally gotten depressed while running. One thing I would like to see on all the tools, as it really wouldn't be much more effort to do, is instead of having speed settings numbered 1-x, label them with the actual speed for that range(especially talking about the fuel tools with 4 settings) as that would make pairing the proper speed for an attachment much easier, as right now I honestly just wing it rather than look at the manual to remember. Last but not least, get us a fuel version of this rotary tool, it really wants to be upgraded like all its friends!