Well, I ordered my Mac Pro today. It will be used mostly for photography and will run Lightroom, Photoshop and Nikon View NX. I don't do any video.
Here's the system I ordered:
6-core
D500 graphics
512GB SSD
32GB RAM
AppleCare
I considered getting 64GB of RAM but, had to draw the line somewhere. Besides, OWC will give me $225 for my RAM if I later decide to upgrade.
Only OS X, my applications and Photoshop's scratch disk will reside on the SSD. All of my images, Lightroom catalog and documents will be on my Promise Pegasus2 R4.
I'm still undecided about which monitor I want. Originally, I had planned to get an NEC PA272W-BK-SV but some of the new 4K displays like the Dell UP2414Q look interesting. It may be Feb or Mar before my Mac Pro arrives so I have lots of time to look at monitors.