How much of a difference on kill speed? Not a lot.
I think with these discussions the bigger differences are in the rest of your gear - hitting 125fcr, max res, fhr, decent +warlock and +warlock skills etc.
In my case I'm using an eth cv insight, clearing p8 while half asleep at 125fcr/maxres and considered moving to fortitude but changing one piece of gear would lead to changing another which would lead to changing another.
Makes sense well said
And very helpful responses from all many thanks