I didn't feel like the QF "uber" really did anything on viaduct tbh, I didn't notice it playing a role in getting big frags or being able to push out of chokes etc. Avoided some krit stickies beautifully but also dropped to some where they wouldn't have if they were running normal uber.
What I'm most interested in is what the teams though of the faster heal rate vs higher overheal factor during the DM fights. Madmen should have had an advantage as they had a kritz at the same rate, which could drop mixup every time using QF, and they had more buffs. In spec you don't really see how fast people are being healed and whether that played any part in the result of fights, did that help or were mixup just outplaying madmen despite the disadvantages?