I’ve used the 9mm on the X7. Don’t like hotswapping. Haven’t had any issues powering it up and adjusting fStop if necessary once fired up. Just sometimes resets camera settings and record formats which isn’t a major deal as I will always check setting later before every flight. I find the trick is to adjust the picture on the ground but give yourself some latitude with ISO. For example, get it correctly exposed or as close to as you can at ISO 200 so you can go either way once airborne if the light changes without messing with the shutter which introduces other issues. Also I find that a Hoya CPL works well and gives the lens a bit more front weight as it appears to be back heavy and unbalanced out of the box on the X7.
Are you finding it sharper when focused a little under infinity?