Hi,
I am one of the authors here. I was doing a google search of my name and found this! With respect to sexual maturity, the majority of efts did reach sexual majority, but were small in size. They were no bigger than other efts, but were able to mate. They did grow to full adult size, though. The biggest factor, though, was the ready availability of live food.
For your information, the newts came from a farm (I am unsure if it is a pond or facility) in Tennessee.
Even though the last post was back in October, I hope this information helps.