That is fantastic John. I think everyone is like you in that they possess the ability to keep consistent angles when sharpening. Bought my first chainsaw in '85, and not once can I say that my hand sharpened chains matched a new Stihl chain. Paying $8-$10 to get one sharpened by a service wasn't a vast improvement over dull either. Sharper than when I started - yes, plenty sharp for the job -yes, sharp as new - nope. Figured that after 38 years if I didn't have the hang of it by now, probably time to punt. Regarding the time it takes, I'm guessing that I would spend 10-20 minutes with a file on a chain with 80+ drivers or a half hour in a car going somewhere. My first chain after setup took all of 5 minutes (feels really sharp, but then they all do after sharpening).
I have the same problem when sharpening knives. I can make them sharper every time, but I can make better use of my time with a guide.
Hoping that the aid of a fixture will allow me to fiddle with angles and depths a little on my own to get me to where I want to be. As you can imagine, if you can't hold a 30 degree angle to begin with, adjusting the grind +/- 5 degrees either way is like trying to push water up hill.