Personally I think males are generally mellower than females, especially if neutered. That's not to say females aren't mellow but I have a couple divas
having said that when I first got into gliders I though females were more mellow...
opinions change due to experiences and time I spose
sometimes gender is just a personal preference.......and sometimes it's not, would I question their intentions of breeding? probably, yes.
Do they currently have gliders?
are your males neutered? if they aren't neutered they may not want the added expense of neutering them if any issues arise down the road.
A lottttttt of people will chose females over intact males simply because neuters can be expensive depending where you live not to mention so many people read online about issues with neuters so some newer owners are intimidated to have it done. Plus intact males smell more.... and they may have read that too
have they met your gliders yet?
If your really concerned you could bring up a no breeding/first right of refusal contract to them and see what their reaction is. But a contract is only worth it if you plan on enforcing it and usually first right of refusals are the only ones that really hold up in court ( last I knew ) but it might at least ease your concerns if they are readily willing to sign one. If they put up a fuss about it your concern is probably valid about breeding them.
Legit rescues almost always use some sort of contract when you adopt from them saying you won't breed and or rehome them without offering them back to the rescue first. Even though your not a rescue you can still do a contract with any potential new owners of your gliders. Anyway it's just an idea, I think I have copies of contracts if you need to see one let me know.
Sorry your having to rehome them