From my experience the hinge of the Cosmo is much more sturdy than the Hinge of the Gemini (At least with my devices). I would say the Hinge of the Cosmo is perfect. The screen nearly does not move when shaking the Cosmo around. With the Gemini I can easily close the device just by shaking it around. This is not possible with the Cosmo (with reasonable force).
My Cosmo screen flops a fair bit, but not as bad as you describe for your Gemini hinge. I can close the Cosmo with a determined flick, but not accidentally.
(normally I close it quite gently, though ... I'm treating it delicately since it would be a real pain to get another Cosmo if I break this one, and it's my daily (only) phone)
I suspect that the factory QC tolerance for hinge tightness isn't very strict. I imagine there are many Cosmos that are sturdy out of the box, and some that are more floppy like mine.
