The only non-obvious feature I can think of is maybe the ability to take two inputs and send them to the same monitor. I know that some people use two monitors because their graphics card can't pass through the 15khz signals from the lower res modes the games use.
Oh, and I remember people complaining about color depth issues with some of the converters. Like 24 bit color modes were really being modified to 16 bit.
Maybe another cool feature would be to have extra control over the resolution. A lot of LCD displays look bad when not displaying their native resolutions. I suspect many people would like the ability to display the image pixel for pixel, or maybe 2:1 or 4:1 for displaying lower resolutions on higher resolution, black bars on the sides of wide displays, etc.
brian
