Personally, I think that, while playing a game, evaluating past positions with a computer gives you a huge advantage. Being suggested a move always means asking "why", and often leads to a change of strategic objectives that often have impact in the endgame, much later. Often Zebra suggests a certain move several times during a game played on the board, and if players knew that would certainly have changed their point of view. Even looking only at past opponent's moves, IMHO, gives a lot of hints on how to play. When playing on IYT I discussed a lot if it can be considered "cheating" just evaluating with a -passive- board instead of pure brain thinking on the position!