I have never been able to explain why some owners never have problems with the latches, including apparently many owners in Europe. But for me, its not a case of if they will fail but when. Even though I reinforced the inner towers with epoxy, I still lacked confidence, and it was always a nagging worry on longer trips. And in fact when I took the assemblies apart over the past month, a few of the towers were showing cracks at the top even with the epoxy reinforcement.
I have adopted Dirtflier's approach and replaced the self tapping screws with lengths of threaded rod epoxied into the towers. I now am about as confident as I can be in the system, and the lids close with a nice secure thunk.
I now feel better about the NT as a whole. And that's really the point. Why live with the uncertainty?
I would either install the threaded rods, or go to exterior draw latches. Otherwise you are never going to be sure.