Leashes who uses them or reasons not to. I haven’t attempted to use it not sure if I ever will. If I do it won’t be till he’s fully bonded.

if he's fully bonded it would be silly to use a leash. He would not leave you, and will seek shelter in your shirt or pocket.
I have heard.
leashes can damage membrane for gliding.
Leashes can be very dangerous when glider jumps and it pulls tight, the jerk is said to be deadly.

With 12 gliders, some bonded, some not bonded at all, I see no reason to ever use a leash. the only danger to loosing glider is outside in unsealed pouch, so never go outside with unsealed pouch.

to dangerous for something completely useless.

No to leashes, for reasons stated by BYK.