Overclocking's just fine so as long as you don't push voltages too far as nc50lc said. Some softwares like Blissz's firmware for the L3+s automatically calibrate to the lowest stable voltage for an overclock, and you can also manually calibrate voltages on software that doesn't do this for best performance. As long as you're running the miner in normal conditions and keeping up with maintenance like occasionally clearing out dust for optimal thermal performance as needed, nothing bad should happen.