Would "half a tonne" make much difference to a Chinook? It's all relative. It may have been that being half a tonne lighter would have meant that they didn't crash, but it also says in the transcripts that they had a 25% power margin - that is 25% more power than they required to hover OGE.
The downwind comment is a little silly. 15 Kts downwind is well within the limits of the aircraft, but not at the end of the approach they conducted-Too fast and too close - within two rotor diametres of the ship!
-Left pedal in the termination to bring the nose round, speed washes off, stabilator programs down?