I use the GTX 970 with the Nvidia VXGI Unreal 4.8 branch. (Do a search for Gameworks Integration to learn more about this)
Most of my career in Arch Viz / Product Design I used the Quadro cards for Adobe, 3DS Max, Vray, and Solidworks. But for Unreal it seems more features/compatibility are available when you use gaming cards, or at least there are more unreal developers working with gaming cards. Today, a friend wanted to try VXGI on his Quadro 4200, and it worked and looks good. But it definitely has some drawbacks in speed/quality here and there.
I also see the big difference using the GTX 970 with Rift development.
I’ve been using the GTX 970 for the last 6 months and haven’t had any (unusual) issues with my existing programs (3DS MAX, Vray, Solidworks, Adobe). I primarily model in those programs and hardly use Vray anymore. I try to do as much visualization in Unreal as I can. I use it for Archviz interiors a lot, and VXGI has really helped me, since I usually don’t have time afforded to Unwrap my objects properly for baking.
Finally, I am also running 64GB ram which has come in handy for doing huge open worlds (Like the Unreal Full Kite Demo). I think you would be fine with 48GB for current arch viz needs, but with the 64GB ram I can easily work in Photoshop, Max, Solidworks, and Unreal all at once. I do a lot of switching between them.