Washington Post has their own reporting from that press bus trip into Douma:
" During a government-organized trip on Saturday, survivors spoke to the AP of the horror they witnessed from a chlorine-like substance that killed their neighbors, but they blamed the rebels for the attack, without providing any evidence."
I think those who stayed wouldn't want to say anything to displease the governments of Syria or Russia. If the rebels had gassed their own people, I'm sure government forces would be displaying stocks of these agents. We can expect "party line" testimony on all sides, however.
I think Assad did use chemical weapons. As a military tactic, it seems to have worked very effectively.
PS: In Fisk's report, I find the following passage a bit curious:
"By bad luck, too, the doctors who were on duty that night on 7 April were all in Damascus giving evidence to a chemical weapons enquiry, which will be attempting to provide a definitive answer to that question in the coming weeks."
Is it coincidence that *all* the medical witnesses were unavailable to the press? Not one stayed behind to care for the people? Did they have a choice about all being taken to Damascus? Is this a public enquiry, or detention?
Quite possibly, what they had to say while in rebel-held territory might not have been the truth. Quite possibly, what they have to say in Damascus may not be the truth.
The truth may prove elusive. But especially unlikely to be found on RT or Syrian news media.