The reason that it is recommended to mount the air cooler after the radiator cooler is that if the tranny is VERY HOT, the water in the radiator is more efficient in cooling the fluid down faster, and then the air cooler will cool it down more yet.
Another reason is during extreme cold, it will allow the fluid to be kept warmer and not get too cold.
There have been a couple members who had valves that would allow changing the flow depending on the weather or time of year. I have been tempted to try some valves which would allow me to try some of the different cooling methods and compare them in different conditions and decide for myself.