I've also had some problems with the Knit Picks cables breaking. The plastic part pulls out of the metal connector, often leaving dozens of stitches in the wake. This has happened 4-5 times and it is sooooo aggravating.
But the truth is, I'm a weirdo and prefer straights over circs anytime I can get away with it.
Except when I make socks - I use magic loop. I have the non-interchangeable Knit Picks Harmony for that and I LOVE it.