Neither the Tern nor Thrasher are what I'd consider predictable. They can vary widely from disc to disc, and I'd never use either mold on a shot where accuracy was necessary.
For me the Tern is quite a bit longer than the Thrasher. Both have the same flight, but the Tern is faster and has better glide.
Star Terns for me are at the very top of the spectrum as far as pure distance goes. I can get them out to 450' fairly regularly. Again, that isn't necessarily accurate or useful distance. Its generally an S curve shot with lots of side to side movement and glide.
The Thrasher is more like a flippy Surge. Wildly flippy, and not extraordinarily long. I'd say the Mamba is longer than the Thrasher.