Why the MintLP seems to us better when it is not?, IMHO because when we use it what we do we do with more accuracy,
I don't think that anyone who uses a Mint LP protractor has every claimed it to do anything more than this. This is pretty much what I replied to Hesson11 back on 4/22.
Assuming a protractor is properly drawn, an arc is an arc is an arc. The Mint is simply made to more precise tolerances. That's it. Nothing more.
Can someone do just as well with any other protractor? Absolutely. Those of us who chose to use the Mint do so because it is easier to be precise, and to repeat that precision such as it is.