Agree, Biphase and NRG2 are not similar. Biphase starts out stiff as a board. At first, you need to take a big cut to get any power, if you don't it feels stiff as board. It loosens up fast though, and after 4 or 5 hours it slowly starts launching everything, then it frays and dies. I found it hard to adjust to the string because it changes so much every time you hit with it.
NRG2 at least stays pretty consistently powerful until it shreds down to just a few fibers on a main or cross. Tourna Quasigut is a lot like that, not so much like Biphase.