You are right it isn't debatable. If you aren't toggling GB in between Buff cycles then you are playing the class wrong. Real application has shown anyone serious about MCH that this is the case but you can easily do some simple napkin math to figure out that having GB off when there are no buffs to pop and GR/Ricochet are on CD is a DPS gain.
AAs are roughly 80~ Potency. You will AA with almost every GCD with GB off so it is safe to assume the you will do a GCD + AA and then you can compare it to a GCD + GB Bonus.
Split Shot - 140 Potency. | GB = 182 With AA = 220
Slug Shot - 180 Potency. | GB = 234 With AA = 260
Clean Shot - 200 Potency. | GB = 260 With AA = 280
Lead Shot - 490 Potency. | GB = 637 With AA = 570
Hot Shot - 120 Potency. | GB = 156 With AA = 200
Starting to see a pattern?
The only skill that loses potency while not under GB is Lead Shot, which can easily be used while under GB since it has a 30 second duration. You can time its application with your GB cycles.
Obviously you want GB on for buffs and every time GR/Ricochet is up but you can easily stance dance when those aren't available which will greatly increase your DPS.
Before you would always stay in GB because it was very hard to re-apply and you would lose a lot of DPS from missing out on GR/Rico but now you can keep those on CD, apply your Dots and use your buffs while under GB and turn it off whenever it isn't needed.
