You won't notice lag except in FPS or similar multiplayer experiences, and a tiny tiny bit of "drag" in certain timing sequences of a handful of games (but this is rare). That said, some DLP's are better than ANY LCOS for gaming (except for dark scenes) for other reasons (fluidity of motion and motion resolution in pans), but it isn't a world of difference better.
The two-projector setup is the best if you can budget it. If going purely off movie watching, you can't beat the JVC in this price range, and that includes the Sony. Sony has smoother motion though more DLP-like on motion, but it isn't as sharp and the blacks aren't as good.
Pick your poison.