It's a good idea, but I wonder how secure larger metal models would be? Personally, I'm not sure I'd trust a penny super glued to a screw would support them well enough, but I'd be interested to know all the same!

I pin all my models into deep bases (3mm+), and prefer painting them off the base; the pins in the feet are a good place to grip with some hemostats while you're painting:

The clamps can be moved and reattached (good if you don't have a permanent painting area like me!), are easy and comfortable to hold (I have big hands and paint slowly...), stable when the model is put down, and - best of all - I can easily get to all parts of the model effortlessly!