What are the positive and negative aspects of taking GHB during the come down of Ecstasy?

My best friend plans on mixing chemical substances this weekend against my advice. I told him I was at least going to look into whether there was any point in him consuming GHB after Ecstasy and the risks associated with it. Any objective information on the effects of doing so, both positive and negative(if I go with just negative info, I'm sure he'll dismiss me and I want to be honest also.) Please, I don't want people just judging my friend, that isn't why I came here...I need information. Thank you for any help.

: http://alcoholdrugstreatment.info/what-are-the-positive-and-negative-aspects-of-taking-ghb-during-the-come-down-of-ecstasy