What W. Tyler said. I read some Amazon reviews of the Weber tool holders this afternoon and the biggest con was with the lid fit. Some said it's more difficult to get a tight fit, but didn't think it was a significant problem.
I won't use a tool hanger or my Slide-aside lid catcher if I'm trying to do a MM indirect cook. That's because if watching temps I want the ventilation to come from the VENTS, but otherwise it's not an issue.