Gamma correction is a way of brightening up the dark parts of the imagery without washing out the bright parts.  We use it with Bing because that imagery is so dark.  The imagery on that gmdemo server is really dark, too, so if that's representative of what people have on their GE servers, then I'd leave it in.  In that case, just change the comment.  "By default this is set to 1.3." is sufficient, since there are no map styles here like there are in Bing.