I know this because I am the one who tested all of the tips to come up with the ratings in the Mueller catalog.
In all honesty, save your money. The idea of testing the hardness of tips was supposed to be used as a reference from tip type to tip type, not tip to tip of the same type. If you use one to test Lepros, for example, you will be all over the board but if pressed or "broke in," most of them test within tolerance.
I know this because I am the one who tested all of the tips to come up with the ratings in the Mueller catalog.