[greglepore]

Yeah, valid point. I had mice access my attic in a prior house and I had a series of ceiling leaks, one on christmas morning, before I figured out what it was. In interior walls its probably a non issue, same with basement ceiling/crawl. If I had unlimited funds I'd run attic pex inside conduit.
As far as commercial space goes, no difference. I'm assuming you're not using a high temp preheater for the dishwasher, or if you are that you'd plumb that with the appropriate material recommended by a plumber as I'm not sure pex is rated for that.