I crank the color(between 150 and 255 on the RGB..remember I use neutral light since my game is b&w), but keep a smaller range. My project uses a Noir light and shadow scheme, and really bright highlights are the name of the game.

Like I said, even if the actual light area(the range) doesn't touch any geometry, the falloff area will influence it a tad. You can control this falloff via script(I think it's one of the d3d_ instructions), but I've found the default is best.

You can make the shadow influencer have a range as large as you want. It doesn't actually emit light, so you can get away with it.