I'm making a base for this, so I could go either way. Lots simpler to go with a thumb screw, and cheaper too as I don't need to hunt on ebay for one of them.
I have seen some where it appears to be a screw, but you give it a quarter turn and it swings a lower bracket out of the way. The screw is about the most unhandy of the lot - as you have to fully remove it (and hope you don't lose it) to flip the machine up for maintenance.