@chakster, never comment on something you have never used yourself.
I have zero problems with the reflective surface of the SmarTractor. I suspect that is because it is perfectly flat. As for the Feikert I have looked at one closely just never bought one because it is vague and I never thought it was worth the money. It is not a fine tool. For decades I used the DB systems protractor. With some modification it is reasonably accurate and inexpensive. The SmarTractor is a fine tool and I have used it. I can not imagine anyone doing it any better.
I have zero problems with the reflective surface of the SmarTractor. I suspect that is because it is perfectly flat. As for the Feikert I have looked at one closely just never bought one because it is vague and I never thought it was worth the money. It is not a fine tool. For decades I used the DB systems protractor. With some modification it is reasonably accurate and inexpensive. The SmarTractor is a fine tool and I have used it. I can not imagine anyone doing it any better.