I need to play with the "temp"gauge on my 260 to see if it makes much of a difference, zero L on or off.
In the summer, I had a trip where I forgot my Kapture group one shot cable and had to use zero latency. The 260 after a morning shoot was considerably warm to the touch, this was in 100% humidity and 95 degree temp. But if I remembered to turn the back off after each set, it seemed fine.
What I found caused the greatest heat build up was Live View, on the 260. With that one, I could sometimes feel the back get quite hot. Where as Live View on the CMOS never seemed to create any extra heat.
Paul C