Dear Mutt,
We operate V2725-A5 IAE engines on our aircraft. I would guess that Tmax flex would differ on CFM engines. I must say that I am unaware of the the 40% thrust reduction as we only operate within the range of 25%, hence my previous post.
Secondly, im not sure of the type of engine you guys operate, however I am certain that the Tref on 319 is ISA+30 and on the 321 is ISA+15. Tmaxflex on the 319 is ISA+65 and on the 321 is ISA+45.
I'm quite sure these would vary on the manufacturer.