I picked up a Toshiba 40" LCD a couple of years ago. It has a "game mode" that almost completely eliminates input lag, but the TV only lags when it's doing its 120hz upscale thing called Clearframe I think. I'll have to do a video sometime with my CRT and LCD running the same game to see if there is still any lag with game mode on, but it doesn't feel like it. This set doesn't have S-Video either, so I've bought an RGB to Component converter, and an RGB to HDMI 720p upscaler. One works better for some systems than others, and one works better on the CRT I have hooked up and the HDMI works better on the LCD.
That said, I also have the Composite and S-Video cables hooked up for all of the systems that normally used them and I found a decent compromise for the S-Video problem. Radio Shack sells an S-Video/Composite distribution amplifier that will take Composite or S-Video signals and output both amplified and in really nice fidelity. Through this thing S-Video downconverted to Composite on my Toshiba still looks great and better than Composite output on that system does. It also enhances Composite signals very nicely whether you use the S-Video or Composite output, and that makes things a lot better for me since I've got most of my systems going through at least two Switcher boxes.