You will be fine with the stock cooler, but for the amount of cash involved and getting away from the worthless push pin mounting system I think an aftermarket cooler is an easy choice. I really don't like the stock mounting system, it's junk.
Try the
XIGMATEK Dark Knight-S1283V it works well and has the backplate included.
When applying thermal paste with the Xigmatek cooler, apply a thin layer across the CPU IHS (top) or across the whole base of the heatsink. The paste won't spread properly through contact because of the gaps between the heatpipes and the base.