A few months back when I was buying the components for my PC, I bought an aftermarket cooler. I had some problems with the PC which required that I RMA two products. When I was putting the PC back together I used the stock cooler instead of the aftermarket one I had bought.
Now, I'm interested in overclocking a bit, and have even done some minor overclocking. The cooler is just sitting in another room, and it's brand new.
With the overclocking I have done, my temperatures at idle aren't very high, around 35 degrees Celsius. I OC'd from 3.1 to 3.5 GHz
If you are planning to Overclock a lot like 300 mhz and up then go ahead with the Aftermarket cooler, and no Overclocking isn't a dumb idea it is a way to get more for less.
I'm also considering unlocking the two cores on the CPU if I can. I'm not sure if these ones are faulty or not. I know that would put out quite a bit of heat.
I've also read about how people have gotten this CPU up to 3.9 ghz stable and am interested in attempting that.
My strategy is to ditch the stock cooler if I'm planning any overclocking, and I'm ALWAYS planning to overclock. Not only that I've used the Xig 1283 cooler and I like it so I'm planning to use it even though a less expensive cooler might work for me.
The question about whether you should or should not change coolers is ultimately a matter of the temps that you get under your conditions. If your temps are OK with the stock cooler, then you could justify staying with the stock cooler.