the "S" lineup are "energy efficient" or "green" cpus... that people buy to pat themselves on the back and tell themselves the $0.03 they saved over the course of a year in power saved some otters or something.
There is no lifespan or turbo improvement by using a "s" variant over a non-"s". The intel turbo is a variable turbo thats limited by threads used, not by heat or power... single threaded things see the highest possible turbo output, multithreaded things see the max turbo reduced.
btw: why would you buy a "z" motherboard and a non-"k" cpu? the "Z" series boards support overclock, getting a non-"k" cpu makes little sense.