The word tantra, states Patanjali, means principal, main. He uses the same example of svatantra as a composite word of sva (self) and tantra, then stating svatantra means one who is self-dependent, one who is his own master, the principal thing for whom is himself, thereby interpreting the definition of tantra.
As DNA Circles get larger and more DNA matches are delivered, more people are connecting into the DNA Circles, which results in more New Ancestor Discoveries, but with a decrease in accuracy. So, we are updating the criteria to make it more conservative and increase the accuracy of New Ancestor Discoveries.
In my opinion the mtDNA test is the LEAST useful DNA ancestry test for most people. Unless you can easily afford to do all three tests, I suggest you invest in either or both of the other two tests before you consider this one.