A friend of mine who works in a Motion Graphics firm said that their company will soon migrate to the Windows PC to replace their Mac Pros. They're getting the HP Z820 : http://www.hp.com/united-states/campaigns/workstations/z820_features.html#.UcFQ6OugllJ
The HP Z820 offers 2 CPUs of up to 16 cores of Xeon E5, has 16 ram slots and can support up to 512g ram and allows expansion. Somehow the PC still offers expansion
It's a nice rig, and when you need a truck, you need a truck... not a Mini Cooper.