You didn't read the question it was 2 systems 1 2500k 1 6100, it's not just the chips
I read your question perfectly.
I am fully aware that you are asking about two systems and not just two CPUs.
However the rest of the systems are some what irelevent, it is the CPUs on which you should be making your decision on. The rest of the systems are very comparable.
The 2500k wins hands down. Everybody else who knows what they are talking about will tell you the same thing. A 2500k beats a 6100 hands down.