New MAc - recommendations?

I may need to replace the studio early-2008 MacPro (8-core 2.8gig) for Nuendo 5.5.3 and Cubase 6

I hear there’s little advantage with 12 cores, better to get fewer cores/faster cpu.

Anyone tried the current 3.2GHz or 3.3GHz quad/six core? I notice the 3.3 uses faster DRAM - I wonder if there’s much difference in practise?

The off-the-wall choice would be the fastest MBP (not the Retina model probably) - I wonder how that would compare? I don’t actually need the PCIe for the soundcard, and I could hang the UAD and Blackmagic cards on a Thunderbolt PCI chassis…

Hang on, I’m dreaming aren’t I?