We just played two rounds before the other pikemen routed. So we never really had time. Though from playing as a pikeman on maps like last stand you truly see the benifit of trenches.
What really bothers me though is that some players insist on having both doors (in the gate) open; 'couse if you have one gate open the bots won't destroy the closed door but their entry point will be smaller restricting the number of enemies you face at a time.
EDIT: btw forgiven and forgotten