IMHO, Allegations of torture are a matter for the Justice Department and Congress to investigate...any more "commissions" would be a sign that it is "business as usual" in Washington. The 9/11 Commission was a double-cover-up, that allowed serious questions to be papered over and resulted in a war strategy that left the US bogged down in Iraq and Afghanistan some eight years after the destruction of the World Trade Center. Any so-called "Truth Commission" would be as unsatisfactory as the Warren Commission in clearing up public doubts (remember LBJ's resignation in disgrace?). It would end up as nothing more than a "Cover-Up Commission," whatever the intentions of its supporters, as anyone who has lived in Washington for more than a few months knows.
Yes, the Democrats were briefed and failed to stop torture under Bush. So what? Two wrongs don't make a right. President Bush didn't pardon Dick Cheney or his cronies, and that leaves the door open for criminal prosecutions and congressional investigations.
The time for cover-ups is over, there really needs to be some actual house-cleaning. When I worked at the Heritage Foundation, they were fond of quoting Richard Weaver's motto: "Ideas have consequences."
So should advocating and approving torture.