very simply this...yesterday the ICE exchange went down!!!....the ICE has no floor to trade out when the electronic exchange goes down...it is all electronic...so, you would have had NO WAY to get out of a position if in one when ICE went down yesterday...if you were in a CME Globex SP trade and Globex went down...then you could trade out on the CME sp pit!!!!!!...there is your answer...BIG time...enough for me...a big lesson was learned yeaterday from the ICE 'meltdown' yesterday...