With an Acer projector (H5370W) the holder does not work once: the screws are too thick. After a long search in the hardware store I've found suitable M3 screws and washers to the projector to screw directly to the round plate - with the poor nothing can be done.
The setting is a bit fiddly, because the position of the projector while tightening the screws a little bit changed, but ultimately the result is very convincing: the projector is held on the ceiling and is no longer moving when the screws are tightened.
Sure there are more convenient ceiling mount - but for the price this one is more than okay!