I picked up a BlackMagic UltraStudio Express Thunderbolt this week, and I'm amazed on how little latency there is. So far I've only tested the composite input. I'll be testing the SDI input next week.
just received this today..feeling excited going to test it with studio livefeed hd-sdi 1080i 50hz tomorrow, hopefully it can perform much better than windows ver. had delay problem with live lips sync performance before with sdi studio usb3
pretty happy with this, so much better than ultra studio sdi usb 3 . tested it during rehearsal yesterday 1080i 50hz. im using imac 21" , 3.1 i7, 16gb ram, 256 ssd, tunderbolt cable 0.5m