I have never heard of this herb, and so did a little research. What I found:

It is a VERY sweet herb that you need very little of in a cup of tea or even in a fruit salad;

It was used as a medicinal by the Aztecs;

Is safe in very small quantities.... like a leaf or two;

the bad stuff is a lot of camphor which can be very bad for the body if too much is taken internally

It does spread by runners, but how fast it will spread depends on climate, soil, etc.

It doesn't like cold.

To me it sounds as bad a spreader as MInt. Not sure I would have any use for an herb with limited use AND is a problem spreader.