Depends which Sandy and Haswell you compare. But sticking to MacBook Pros: Haswell i7-4750HQ and Sandy Bridge i7-2860QM the difference is pretty small.
http://www.notebookcheck.net/Mobile-Processors-Benchmarklist.2436.0.html
Number 36 and 42 on the list.
I know both are i7
😉 But you should compare processors which are similar in application. Both were in Macbook Pros.
Maybe specify what procs are you talking about exactly?
The 2400S is a processor with lower TDP. I mean lowe then a standard 2400 cpu.
To stick with metaphors:
The i7-4750HQ and i7-2860QM are big tracks full of load. Delivering stuff in one big slow package.
The 2400S is a small truck, speedy, and it uses much less gasoline. And is not destroying roads delivering stuff (is not heating whole computer)
It all depends what you need?
😉