I'll shy away from the human part of these calculations as i don't ever get more than 50ms in raids and i'm very thankfull for Apple making a metal keyboard as it sees a lot of button bashing.
Isn't a .1 sec delay on Immo hitting the GCD now and then worth less then the extra Incinerates you get to cast during the same fight length with a higher amount of haste?
Also, my Incinerates during Backdraft are at 1.2s cast time and i'm not stoping untill i get them at 1s. And Backdraft also lowers the GCD by 30% so you still have .33s to spare for lag or reaction time...
I would be a very very happy lock if i can get both this and DFO! But seeing as i have the worst luck in trinkets i probably won't get either one