I also reversed my fan (same place) and get cooler temps. but I positioned my two 120mm HSF fans to suck the air in and out through the HS. What ever works works

Yes, I reversed my side fan and it lowered my gpu by 3 degrees celcius, then I placed a PCI card right under it and it went a whopping 1 degree back up. It stays at 38 now.

Consider another environment; How to cool a room?
Blow air in or face the fan to evacuate the room?

The 'evacuating hot air' as a principle is more effective in lowering the room temperature when another source of air can be used to replace it.

The need to cool the heat sink, is quite a different matter.
That device is designed to be a radiator and thus needs air flow to pull the heat off
so it may continue to absorb heat generated by that xxx ghz device.

Given a choice, the HSF blows directly on the device, but the case fan should
evacuate the 'room' (ie your case).

Alas, there are many studies which show case fans are only marginally effective at best... It has to be special fans in very well designed locations.
The CPU fan, on the other hand, is so critical that even a slight change in position or of thermal paste can make a difference of 7 to 9 degrees... and brands of cpu fans (models) can even make a difference of 13 degrees, depending on blade design and a clear channel to move air out of the area.

I'm willing to bet if you took out my case fans it would casue my GPU to get to excessive temps, considering the way my rigs laid out. Its micro atx motherboard in full atx case, but the cards are so close together.

If you were to trace air flow within a computer case, you would find that when you insert a card it creates an "eddy" within the normal cross flow from front to back in the case.

That's the beauty of Antec"s 900 gaming case.The emormous fans simply saturate the interior, not giving hot air any place to hide.

Yes, I love that case. I think I will stick with mine until I hit the lottery, though!

And then there's the Thermaltake Armor ++.