I've a love hate relationship with the QF as if they Pop at last with a comitted team, you're pretty screw (unless you've uber or QF ready) The QF charge (and healing speed) is very fast making it easy to come back into a fight, instead of say Uber where it take quite a bit to charge and you know where the stalemate happen, HRG is patience with their approach so no surprise that long stalemate happens. Shade actually die a lot using QF which is something you don't see happen very often. So is the Vaccinator banned? I would like to use it to counter Kritz.
My other opinion: it allow teams to be somewhat agressive with their push, get to mid fast by jumping around with the demo, solly or high tail it out of dangerous situation pocketing a scout. I agree the buff need to be balanced out just a bit for 6s, I tell ya QF in HL is tricky to pull off (well I ony tried it 3 times on MixHL so idk if it is truly effective) as there's gonna be lot of shit shooting at you.