Push Vs Pull - This depends on fan speed/power. The high speed
fans at 2000RPM with a 38mm fan thickness provided the best performance in a push condition. The slow speed
fans with 1350RPM with a 25mm fan thickness provided the best performance in a pull condition. I would estimate that performance line is likely to cross in the 1500-1700RPM range where they are equal. So.... slow speed = pull, high speed = push, medium speed = it doesn't really matter.