Hmm.
I am currently on a quad core and intending to upgrade though now i have reservations.
Steinberg has made big improvements and its engine is certainly quite good at cpu consumption,maybe even at the top with Reaper,though i havent tested anything with more than 4 cores. Funny thing is in the end of 2016 we can expect major breakthroughs in cpu development,as both Pentium and AMD will reveal new line of cpus.
AMD claims to have made a 32 core cpu for a single socket,engineers at CERN have already tested it,supposedly it`s a beast.