Mandarax, your mount looks like something I'll be needing in a few months. I have a very high vaulted ceiling and wall mounting a projector just above my couch is what I'll probably need to do.
However, I'm interested in one modification. I'd like to have one where the plate that attaches to the wall is permanently afixed to the wall but the support arm that extends out from it (including the projector) can be easily removed. Yes, I'd like to be able to 'lift and unhook' the entire support arm with the projector and all whenever I don't want it to be hovering overhead in my small living room but leave the plate that's attached to the wall where it is.
I suppose I'm imagining some type of sturdy but quickly and easily removable connection like you'd find with an adjustable shelf in a retail display set-up. And like those kinds of shelves, some ability to re-position it a little higher, lower, left or right as needed could come in handy as well, assuming the permanent wall plate would be large enough in all directions to accommodate that to some minor degree.
That way, I could simply reach up, slip the entire system off it's wall mount and set it aside on a side table when not in use for security reasons, living-room esthetics or when maintenance or lamp replacement is required.
A decorative, framed 'camafluage' surrounding that permanent wall mount may also be in order too but that would be a seperate fun project I could add later.
Any thoughts on this?