I've been doing them for about a month now, with 55lbs added. So far so good, but I can feel the strain on the joints quite a bit. At the first sign of trouble, I'll probably go back to close grips for a while.
But I've been doing the weighted dips on the 5x5 workout, and I couldn't be happier with the progress. I remember a time when I could barely do five or six good dips with just my bodyweight.