Any Thunderbolt docks compatible with 4K at 60Hz?
I have an AMH 399U capable of 3840x2160@60Hz with its DisplayPort 1.2 input.

If I connect my AMH 399U to a Thunderbolt port on my Elgato Thunderbolt 2 Dock, with a DisplayPort to Mini DisplayPort cable, I can then connect the other Thunderbolt Port on the dock to either my iMac15,1 (Retina iMac) or my MacBookPro11,3 (15" Retina MacBook Pro), and I get 3840x2160@60Hz on the AMH 399U, with either Mac, the same resolution and refresh rate that I get if I connect the Mini DisplayPort end of the cable directly to a Thunderbolt port on either mac.

I bought both the monitor and the dock on Amazon. They can be seen at http://www.amazon.com/gp/product/B00PAPMSLE and http://www.amazon.com/gp/product/B00XTVGM7C