All the Intel chips overclock by design to a point - it's what the "turbo-boost" feature does. They seem solid regardless.
As for cpu speed, I've a Macbook Pro 2013 model that runs pretty hefty projects in Logic without issue using a 2.2GHz I7 (and only Intel HD4000 graphics). Cpu speed ceased being the biggest constraint on performance a few years ago. The only exception I've found being Amplitube which seems to consume far more resources on OS X than Windows for some reason.
As for stability, my suggestion is not to buy the latest and greatest motherboard but one that's been out long enough for the faults, if any, to turn up on forums etc. The motherboard in my sig was a fairly new release when I bought it, within a few months there were lots of people all over the relevant forums with apparently random lockup and freezing problems which not even manufacturer BIOS upgrades solved - and the manufacturer has never really acknowledged the problem.
I was lucky in that my board didn't have that problem. Until the end of last month, that is. :-(
Updating the motherboard also means a new cpu (can't get a decent board with the required socket for the existing one), new RAM if best performance is going to be had, and so on. The only thing I use Windows for these days is Sonar and I'm getting very tempted to just put Windows and Sonar on one of our Macs...