Not sure what do you expect from a protractor, but no not overestimate the importance of it. You cartridge can be aligned perfectly even with FREE protractor that comes with Hi-Fi NEWS TEST LP.
I can't use mirror protractors, for my eyes it's better to see white lines on black surface and alight according to those lines than white lines on mirror, on the mirror you will see the line and reflection of this line, I hate those protractors with mirror, they are useless.