The problem dealing with beta on the garette is that it means something different to the free turbine types.
Yes it means that reverse pitch on the blades is available but it also means there is a swap in shall we say dutys of various controllers.
So beta isn`t really a range its a engine prop control mode in which beta AoA of the prop blades can be used and is available. I think it also does something to the oil system supplying the beta tubes to increase the available pressure to protect against rev in the air with a prop pitch controller failure. But will check that tomorrow.