Martin did a test that found that pull/pull (without shroud) essentially doubled the static pressure for 25mm fans. That sounds pretty effective to me. Push without a shroud is going to have a very large dead spot in front of the hub, especially with a 38mm fan. I'm not sure why this LED thing is so important to you. It really limits your selection of fans. Just buy separate LEDs and hot glue them to the fans wherever you want them. There are also small LEDs that mount on a small swivel which you can aim wherever you want for spotlight effects both inside and outside the case.