My 30 foot Key Digital cable is spotty at best. I've been quite disappointed with it.As I wire the AV room in my new house, I'm testing cables to find a long one that works as well. I got a 35' one from Key Digital (http://www.keydigital.com/Downloads/Champion/Commercial_ProK_HDMI_Cables.pdf) as the specs say it should pass the full 18.0 Gb/sec signal and a friend that does CI work has had success with them.
From the Samsung player to a receiver (multiples, I'm doing reviews right now) or to the Vizio P65-C1 it works great. From the receiver to the Vizio, it totally fails. Same if I put the HDFury Integral into the signal chain to try to read the EDID, but it just isn't working. So either those devices aren't putting out enough voltage for it to work correctly, or something else. Using the passive 20' Monoprice UltraHD Premium cable (which is used for my projector typically) it works fine. Ordered the Monoprice Cabernet this morning and it will arrive Tuesday, and then I'll see if that works.
The KeyDigital is failing off the receiver even when using 1080p content from an AppleTV, making me think it's more of a voltage issue from the receiver than an HDMI 2.0 bandwidth issue, but I can't be certain. Checking with the receiver engineer to see what the voltage is and if that could be a possibility. But this is a huge headache for people.