My experience with a grinder has also been that it takes pretty much the same skill to sharpen well as it does to file by hand well. I almost went back to hand filing after that experience, but the grinder is easier on my hands when doing several chains for a few hours, and I trust it to get the teeth the same length more accurately than me eyeballing it. There were many inconveniences with the grinder I used. One was having to re-dial-in the length it would leave the tooth after grinding when I switch from doing one side of the chain to the other. It wasn't as simple as flipping the chain around or the grind angle, the chain advance distance had to be readjusted. There's just so many variable involved as well as tolerances of the grinder to worry about. The one I used didn't seem flimsy, but flexed enough to have horrible precision. There was almost no way to accurately set depth gauges with it, because I thought it would stop at the set depth, but the frame would flex so much that I couldn't feel when it hit the stop. The chain clamp was sloppy. It would only pinch one little area, so the vibration and pressure of grinding would tilt the cutter back. The only good thing was it had a reverse switch, so you could get more even sharpening results.
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