I use on the Epiphan without the compression mode. With 800 x 600, I got like 23/24 frames, in 1024 x 768, drops to abou 16/17 fps, what for most of PPT presentations, goes pretty well. I am looking to buy a new Epiphan card, with the compression mode 30fps on any resolution. The box I have has not that option, just uncompressed, nut can capture either DVI or VGA.
Gian