Okay, got a few insights after playing around with the CAC 1070 adapter.

Setup:
Windows 7
Nvidia drivers v 361.43
2x Nvidia GTX 680
Dell 3007WFP via DVI
Dell 2007WFP via DVI
Samsung UN55JU6500 connected through a Denon AVR-X4100W

New or old firmware made no difference.  Originally I had SLi enabled, which forced me to connect all three monitors to the same graphics card.  Nvidia drivers only allow output through one graphics card when SLi is enabled.  This only offered me 4K@30Hz through the adapter, which was detected as HDMI and not Displayport.  Disabling SLi and then attaching the adapter to the other graphics card enables 4K@60Hz.  It seems like there’s a limitation (at least with my graphics cards) where Displayport output is not enabled unless it is the only display attached or there is a maximum total output bandwidth.

In any case, it seems like a limitation either with Nvidia’s drivers or the graphics cards. Adapter works fine.