Have a Silvey at work, going to get the hang of it eventually, been about 15 years since I used one. Hand filed all my life. But recently due to maintaining all the county saws, and everyone needs to be sharpened, almost every time! So I have been using the Stihl, and a Grandberg 12v portable. Very impressive results. 40 bucks too.
The cheap harbor freight sharpeners are pretty good for someone like me that just cuts a few cords a year I mainly use it to clean up a rocked chain or to get the neighbors chain back in shape after he has filed every tooth at a diffrent angle