I'd take an iMac over a PC any day of the week except for running X-Plane..
I understand that, but as much as I love X-Plane I'm not getting a PC for it.
As there still are some rumours regarding a new Mac Pro, I'm holding off getting a maxxed out iMac 27". Once I'm sure no new Mac Pro is coming out, I will get the newest and fattest iMac...
My good ol' 2008 Mac Pro (8 x 2.8 GHz, 16 GB RAM) with Radeon HD 5870 still does pretty well in X-Plane 10.
I might even get a HD 7950 (if it's compatible with the 2008 Mac Pro...) X-Plane 10 with HDR lightning will take advantage of that card, I'm sure.
It does get frustrating though... waiting for clear signs of a new Mac Pro...
I would love to set the grfx settings higher and be able to fly smoothly over the expensive scenery I have purchased the last couple of months...