I used to have an old A frame stand back in the day, and the main complaint I had with it was simply that it was next to impossible to dial out the 'bounce' unless you supported the keyboard front AND back.

Think about it for a minute.... You are balancing a keyboard on a single tube of thin aluminum. No matter how tight you crank the end caps, there's some inherent flex in the tube itself, in the joints, and especially in the arms that go through the tube and support the keyboard. It used to drive me crazy!

Admittedly, I'm from the old school, I learned on piano and organ and Rhodes, none of which move a millimeter if you pound them with your fists! But also there's the issue of velocity... A keyboard works out how hard you are playing it from the speed at which the key goes down. But if the entire keyboard is going up or down a bit when you play it, that speed is added or subtracted from your finger speed depending on the bounce's direction. So your dynamics are a little bit less precise. Not ideal...

It might be worth checking out any local musos that play on an A frame, and see if the bounce is acceptable or not...