A new retoucher told me that I need to change my colorspace on my 5D2. He says srgb is not as good as Adobe 1998?
Shoot raw, it doesn't matter what you set and you can get an even bigger color gamut and always convert to sRGB or other down the road. Here's why:
Everything you thought you wanted to know about color gamut
A pretty exhaustive 37 minute video examining the color gamut of RGB working spaces, images and output color spaces. All plotted in 2D and 3D to illustrate color gamut.
High resolution: http://digitaldog.net/files/ColorGamut.mov
Low Res (YouTube): http://www.youtube.com/watch?v=n0bxSD-Xx-Q
OR if you must shoot JPEG, set the camera to Adobe RGB (1998) and again, you can always convert that data to sRGB for the web (the only real useful place for that color space).