Being able to feel a change of +/- .015 is remarkable. Do you do neurosurgery on the side? You probably could.
I assure you that I am nothing special in any regard. The neutral and level flight can be way off and still be able to fly. When Ted and I, er, Unknown Pilot #1 and #2, flew the ARF Strega before and after the line carrier had slipped about 1/4" - unbeknownst to us. We heard a "twang" during the pull test, looked at everything, and didn't notice anything wrong. Then we flew it. I couldn't really tell the difference, it felt a little odd but not way off compared to all the other issues it had. Ted said it "felt squirrely", but nonetheless flew a very competitive flight. After a few hours, I figured it out, and then we had a debate on whether or not to change it back. This all in the middle of a contest. I think we left it alone.
Same thing at the 2008 NATs. My regular handle had fallen out of my toolbox and been left at the field, so I went to find it the morning of qualifying on Wednesday. No handle, so I grabbed the handle I had for the Skyray, eyeballed the neutral, and flew it, no practice. Neutral was close enough (since all my lines are within 1/32" of each other), but it felt a little "slow". Someone found my handle and turned it in, so I got it back. The spacing was 3 notches on each side larger, about 3/4".
The difference between that, and the situation I am talking about, is a matter of concentration. Had I needed to fly with the handle as I showed up with it, I could have done a decent job of it. But changing it just made me feel more comfortable in terms of control loads, particularly on the outside rounds and a few of the outside corners. I had been doing competitive square 8's, for example, but my 1/64' or so change made it go from taking some extra effort to get the left lower outside corner correct, to being automatic. The airplane is typically a square 8 machine, if it takes a lot of effort, something needs to change.
Brett