So to sum up I think we can all agree that macbooks look cool and that bootcamp means I'm not special; that I should buy one over the interwebs, install wow and see what happens as I can return it if it doesn't make me look hip?
HotS is running on a way more modern engine, unlike WoW which can be run even on a toaster. I wouldn't recommend it as a main machine for WoW, but at least it's gonna be somewhat playable, unlike HotS.
Yeah, MBP should be ok (just don't play on @2x :P).
That's not even true anymore. If you look for yourself on the HotS and WoW pages, WoW has higher minimum spec requirements. Spec creep on WoW seems to have been quite substantial to the point where Ironforge is probably one of the lightest areas in the game which is a stark contrast to back in 2005 when it used to be the one area that killed toasters.
The last time I looked via MSI Afterburner, MoP areas load the CPU and GPU a lot more than pre-MoP areas and WoD areas even more than MoP areas. If I had the expansion right now I'd check the new areas and my guess would be the demands are even higher.