@Schube30 The information you are getting regarding the 2550K is assumptions and not accurate, the 2500K is a much even across the board overclocker, I actually know from my own experience, because I own both and have individually tested both.
I already had the 2500K and bought the 2550K to upgrade my wifes platform, but if the 2550K was a better overclocker I was going to keep it myself and give her the 2500K, the 2550K is a horrible overclocker very tempermental, so my wife gets the 2550K as planned because I won't be overclocking her new build.
She is not getting my 2500K that bad boy is staying right where it is!
For overclocking purposes I 100% recommend the 2500K over the 2550K! Ryan