I have used the 4-40 rod ends and carbon fiber rods with great success so far. I doubt that they could ever pull apart. I think that something else would pull apart or break long before the rods will ever come apart. I would prefer to use the titanium ends but don't want spend the extra $ on them. I used to work as a materials tester at Boeing (still work at the big B but work in a different department) and would tensile test lots of different types of stuff. I remember when we would get in some of those electrical zip ties in to test and even the smaller type ones that are about 3/16" wide and about 8" long would tensile test at over 50 pounds. Anyway, the metal rods that come with the U Can Do bend too easily and are best replaced with a carbon set up. IMO