Do you know if the BlackMagic Intensity Shuttle for Thunderbolt can do this with no lag?I use an Avermedia ExtremeCapU3 to play PS4 on my mac mini/Thunderbolt display works great no lag.
I believe the main difference between the devices is the max framerate - 1080p60 capture for the ExtremeCapU3 and 1080p30 for the Intensity Shuttle. Whilst currently I have a monitor with a spare HDMI port, eventually I hope to have a 5K iMac with one of these capture devices essentially acting as a HDMI input