My main capture for the OSSC is a Datapath E1S which works with anything that you throw at it.
For my laptop capture I was using a Avermedia LGX previously with a framemeister, which worked well at 720p, but when I switched over to the OSSC it could only do 2x 480p, and would glitch out every so often.
But I have good news! I picked up an Elgato Cam Link, and I can confirm it works perfect at 2x, 3x, and 4x. It could possibly work with 5x with some further tweaking. http://a.co/b5r21Ob