Although you may feel safer in a heavier boat, if you keep all other things equal, the lighter boat will be safer in heavy weather. It will, however, need to depower earlier due to the lower righting moment.

Why you feel safer? Most beach cats can't be reefed, so the later you have to depower, the safer you feel. But it is a dangerously false safety feeling: the heavy boat is submitted to higher loads and, as a consequence, is more likely to break something (compared to the lighter/depowered boat).

The answers are outside the water:
1) From a reliable source: a folding tri is exposed to higher loads when trailered than in a squall.
2) User abuse, as already posted here.