How many folks spend all their time grasping the brake levers? 99% of the time my hands are not on the levers, so any " thermal conductivity " is essentially nil. Likewise, how many folks ride without handlebar tape? Most people use the foam variety, effectively 1/16" - 1/8" of insulation.
I do love my Campy Chorus 8 speed setup. 20 + years and it is still perfect. Can't ask much more of that and only strengthens my 38 year attachment to Campy.