According to testing, the difference is indeed twofold, and sometimes even threefold
So you rlly think that classes have been nerfed by 50-70% in one single patch? I mean, you are basically saying that if you dealt like 20kk with a hit before, you now deal 5-10kk, but the only things that have been nerfed for m/w are exactly these:
Quote from patchnotes 12.1.0.4000
Mage/Warrior
- Reduced Raging Field base damage to 3663 from 4324.
- Reduced Raging Flame CPS damage to 123% from 144%.
...which is (with my limited maths knowledge) about 15% nerf each time.. but raging field flat dmg is only like a third of its actualy damage bcz most of it comes with the CPS hit, so it's just worth like 5% overall and raging flame is another 15%, but overall maybe 10%(?) - I think raging flame deals something around 30-40% of overall damage, but not sure, so both together are more or less 15-20% (rather 15), and that's exactly what I noticed in my runs.. and I'm not even that active atm to get the idea
so whatever u did in your tests, you did wrong 
About the gear scaling.. uhm... u know that mage gear doesn't scale the same way as pdps, its much more linear for us, so gear difference isn't rlly a thing in dmg, at some point it's even just about convienience or survivability. I have a t18 staff and most gear is mostly t14 and I feel literally no difference to a t16/12 one of a guild mate (or the 17/13 I had before). Just some cooldowns are faster due to cdr roll and I survive more hits.. t16 vs t18 weapon is maybe, just maybe 10-12% more damage (depending on rolls).. I think you're just exaggerating wildly..
PS: @devs you forgot a gd note there! Literally unpl... ok I stop it
pls no ban 😱