Judith,
I wish that the structal flaw was the greatest weakness of the IPCC. But IMHO it is not. The whole idea of the IPCC is conceptually flawed. The idea that there should be a single organisation that authoritatively summarizes climate science is flawed becaues it then becomes argument from authority. Which it has.
If we want summaries of climate science then groups of climate scientists will publish meta-studies. Then we would now be seeing competing pro and skeptical CAGW competing and as evidence improved the answer would emerge. Just as it always has done in science.
The policy makers would hate this but tough. This is the real world
/ikh