I have read elsewhere that the VPI alignment tools made for their own tonearms are error prone. This is not first hand information coming from me. Check threads on Vinyl Asylum.
I don't like the Turntable Basics protractor (sadly, I own two of them), because the protractor does not extend to locate the pivot precisely with respect to the spindle; you have to line them up by eye. For not much more cost you can find protractors that fix the relationship between pivot and spindle; that's of key importance. If the Mo-Fi Geodisc is like the TB protractor in that regard, I personally would avoid it too.
I don't like the Turntable Basics protractor (sadly, I own two of them), because the protractor does not extend to locate the pivot precisely with respect to the spindle; you have to line them up by eye. For not much more cost you can find protractors that fix the relationship between pivot and spindle; that's of key importance. If the Mo-Fi Geodisc is like the TB protractor in that regard, I personally would avoid it too.