The only time I broke anything was the phillips head on the original Leatherman and that was beacause I was trying to undo a screw on a rusty engine and torqued it to much. Leatherman replaced it with a Blast model free of charge.
I am willing to bet the only reason you see alot of threads of broken Leathermans is because people tend to post more problems with their tools then they post good comments. If you ever did have a problem, Leatherman will take care of you. They have a 25 year warranty.
Every company can have a bad batch but I wouldn't let those threads worry you. Besides, there are some people, not alot of people, out there who really don't like Leatherman and can't wait to post a problem with one just to try and make them look bad for personal reasons.
I currently have three and looking at getting a fourth one and haven't had anymore problems other than the original phillips that I broke. I have a Micra, Blast and a Supertool. I am thinking of getting a Core or a Wave, can't decide.