I hate push pins with a passion! I do not know who thought it was a good idea to use something like that where the cheap plastic pins can break easily.

I think the stock heatsink is decent for stock IF you clean off their thermal compund and use mx-2 or ac5 and have a well ventilated case that has great air-flow.
other then that I would not touch the stock heatsink for any overclocking or if you have a bad case with limited air flow.