LOL at the last comment. :lol: Anyway, nah, the 2550K wouldn't run any cooler, since you won't be using the iGPU on the 2500K anyway (uses no power and thus, creates no heat, when not enabled). I imagine you won't be using it anyway, since you even put the 2550K into consideration.
The Silver Arrow IS just slightly better, but not enough to make or break an OC. That choice is up to you.