Most of the guy's arguments against IGH and/or belt drive are pretty thin, pointing more towards the poster's own questionable mechanical competence and a preference for light weight (nothing wrong with that) than anything else.

@alans-
I just want to clarify (as one of he "some" that has used belt drive and chosen to go back to the chain) that I personally feel that the belt is a pretty brilliant system with quite a bit of potential, particularly for SS applications.
I do believe the jury is still out for the combination of IGH with belt. I personally found the "feel" of the chain with an IGH to be much better than the belt/IGH, and I think the tension was the primary factor.
If I lived in a climate that was really salty or slushy, I would probably end up going with a belt, as I feel the belt is far superior to a chain in these conditions.