Pixhawk orientation?

Not sure whether to post here or to the Pixhawk forum, but here goes.

Does the Pixhawk have to be mounted completely level? I know it can be mounted in different orientations like upside down, but I’m not sure if a small (or large) inclination will affect performance?

Ok, I have no idea how I missed the 3.1.0 subforum, but this thread should obviously be there.

Anyway, it looks like the Pixhawk doesn’t have to be mounted level - after running the accelerometer calibration, the horizon looks like it should (plane level = horizon level). But this leads to another question: why is there a parameter to set the orientation when the accelerometer calibration could determine this as well?

Btw this is why I missed the right subforum (it’s not listed on the front page).