Having just ventured into 4K monitors, (Asus PQ321Q) and having to send it back after a week of messing around with Asus support, who were responsive and timely, but ultimately could do nothing. I heartily agree that its a Wild West out there, and not ready for prime time just yet.
It seems FirePro cards are not properly supporting 4K @60Hz, (W5000 in my case, which according to ATI does support 4K) Most people here would want to use FirePro, for the 10bit capability (at least those with Windows) which works great with a full hi-bit pipeline on NEC monitors. These displays (Asus, Sharp, Dell) are all 10bit, but cannot be driven that way as yet effectively.
I'll hold onto my $ till the single channel (non MST) 4K monitors come out, and preferably an NEC one, with proper Spectraview support. Might get a 4K TV though - that will be fun to watch.
Sorry - and back to OPs question. I would go for the NEC. I read an extensive review on line, which basically said it was flawless.
