get 2 machines then. Who says you need to have a single machine for everything? Get a Mac for your design work, treat it like an appliance, and use Linux for everything else on another machine. Problem solved.
While I like your solution in principle, I can imagine it complicating life awfully...
People email you assets/images for use in your production work: are you going to get that on your 'designer' machine or on your Linux box? Most likely the latter, now you have to transfer it over to the 'work' box. Not technically difficult, but a definite speed-bump in your workflow. Awkward.
Your online document-sharing/demos (say Dropbox, whatever): is that from the work box? the utility box? both? Again, not technically a train-smash, but... awkward. A discontinuity that you'll have to deal with multiple times a day, a detour in your flow.
I can see why many would consider it too much of a hassle.
get 2 machines then. Who says you need to have a single machine for everything? Get a Mac for your design work, treat it like an appliance, and use Linux for everything else on another machine. Problem solved.