Actually, I recently compared the 727-100 block hour costs with a 737-300 on a 1300nm route. The 727 burns more fuel per hour, but takes less time to cover the distance. This also means less engine hours, lower maintenance cost, less crew hours and overall, a lower block hour cost than with a 733.
Knock out the F/E position and they're even more competative. Long live the 727
