I can not speak directly about pennywort, but I can say that you may have to decipher the web's opinion on many plants. "Evasive" plants to a gardener or landscaper can mean something totally different to a pond mister.

I have transplanted moneywort to my pond and the web says that it can be evasive, but most of those reviews were from people you can not contain it in a flower garden. I, on the other hand, want it to fill in around the shoreline and be kinda evasive in the sense that it grows and spread quickly to help with erosion. It will not be evasive in my situation (IMO) as it will want to live very close to the water and not spread up the bank where the dryer soil is not conducive to it's well being and it will not spread into the water to the point of crowding my emergent that I have established.

Bottom line is, try to determine what the web reviewer's goals are when deciding if the plant will be "evasive" for your situation.

Fish on!,
Noel