Bb to A quick change still useful?
I have a couple old horns with a Bb to A quick change valve. I’m just curious if there’s any real reason I shouldn’t use this feature if, for example, i’m busking or at a jam, and somebody calls a tune in E major(concert). Couldn’t I just pull out the quick change and try to play in G instead of F sharp? Is there a good reason not to do that?