Mostly true. However when in recirc mode, your cabin will always cool faster at max fan. All other theories are myths. When pulling in air from outside, there is a balance between max air flow with medium temp vs min airflow with cooler temps at the duct due to the fact that you can only take some much heat out of the air in a single pass. But, that doesn't apply in recirc mode.
Also, I've put temp gauges all over my AC system in my '09 with the same goal as the OP (Texas can get stupid-hot as well). I found that our systems can take a little more than 30 degrees F out of the air when the humidity is low. The real trick to good AC performance is to get it into recirc mode fairly quickly but first tilt open the sun roof to let the scalding hot air exit when you first get in. After a minute or so, you can close it and just stay in recirc mode until you are nice and cool. I've been researching some zeotropic refrigerant alternatives to try to improve heat transfer performance across the evaporator. Pure propane is an interesting additive to an ac system. So is mixing in other specific freons. The whole effect is greater than the sum of the parts when mixing them. If I get any meaningful data before I completely destroy my system, I'll post up the results.