They all have some lag involved. Whether or not it's noticed depends on how exacting you are. But the nature of the beast is that there is some signal delay because getting the picture to your monitor is a two-step process instead of a one-step one.
The EyeTV EZ might be completely playable since it's more simplistic, so the delay is minimal. But if you put a computer TV tuner and an actual television side by side tuned to the same channel, you will notice that the computer is behind. I've tried this with 3 different tuners (both internal and external) on the two computers in my signature, the dual G4 1.25GHz I used to have, and a G5 iMac. Even with direct pass-through, the signal still has to be digitized and passed from PCI to the graphics hardware.
In fact, just to test this out, I used a signal splitter and picture-in-picture to pass one through the computer and one directly into the monitor's input. You can see in the side-by-side that the one going through the computer is several frames behind. It was still playable, but there is a difference. It just depends on your standards.