No, they really don't have a grasp on the subject...
First off, they won't accept any investigation that says, "Yeah, the 9/11 Commission did its job pretty much by the numbers, and 19 guys with boxcutters and a penknife to grind against the United States did the job, and the US government ineptly ignored the warnings."
Second, they won't accept, as other folks here have mentioned, anybody on the committee who has any ties to the government or any organization that says the above. So that wipes out 99.999 percent of the world's scientists, engineers, chemists, physicists, cops, and fire investigators. All you have left are guys who wear tinfoil hats and think that the other CTers are just government shills.
Third, because of that paranoia, they won't be able to agree on anything short of the idea that the US government is evil and "did it."
Fourth...and this is the big one, to me...these guys are essentially lazy. The whole tactic of CTers is to make someone else do their bloody term paper. Their whole behavior is to make that 99.999 percent of the world's scientists and technical experts stand up and prove the CTers wrong, instead of the CTers having to stand up and do their research to prove their theory right. They prefer to put us on the defensive, and make us jump around to their tune.
That's because they have no facts, no case, and no real importance to the world, and they know it, so they get a lot of their jollies from their CT stuff from the fact that suddenly they can get attention and make other people react emotionally and grant them an importance they do not deserve.
Try asking the CT nutters what they would like to replace the US government with, and what they would do if they were running the US instead of the Republicans or Democrats. What's their policy on tariffs, the environment, the Mid-East, the economy, poverty, public transportation, housing, and defense? Besides blaming it all on the Masons, that is.
They don't have a clue. So how can they investigate anything?