I guess I'm in a contrarian mood, but I'm not too impressed, maybe because in one of the bands I play with, 3 others have Peterson tuners, all of them the stomp box. Most of the time, one or more of them is out of tune. Disclaimer: I do have a tuner hooked up all the time to my guitar. When I need to use it, I do. I don't have any problems tuning any of the six psgs in the house. Just my 2 cents.
I would be lost without the stroboflip. SWT E9th is as close as it gets, whatever guitar I have tuned. You must tune any of the strings that are lowered (ie. 4th, 8th, 1st, 6th) on my steel) to pitch after releasing them from their lowered note. So tweak at your tuning peg, lower string then release and take your reading, if its flat, tweak lower, release, and check the reading. This must be done. Try it yourself.. If you tune an E (4th) to pitch without doing this, when you lower it and release it, it will always come back sharp.. Who knows why this happens, I have never seen a steel that does not have this characteristic... Is it the nut/roller ? or is it the changer..? Or the string itself ? Or ?