If you've played MP before this link is probably of no use to you:
http://www.subsim.com/radioroom/showthread.php?t=105486
Suffice to say, GWX 2.0 is very new and people may have added a little something to tailor fit their own preferences (I certainly have).....and as you well know, that is all that is needed for a MP CTD.
All I can suggest is you speak to the people your going to play with beforehand to ensure you all have identical setups