<VV> AC Recharge Question

[RoboMan91324@aol.com]

Hey gang, 

The hot weather is coming and I need to recharge my AC.  I will attempt to 
reseal the seals, etc. to avoid tearing down the system.  However, my question 
has to do with the replacement coolant that has been recently introduced.  
Enviro-Safe, Freeze 12 and MacFreeze (No, that isn't a McDonalds dessert.) all 
claim to be replacments for the original R12 freon.  Some claim to be superior as 
far as thermal and environmental characteristics.  Another benefit is their 
cost of purchase and the avoidance of retrofitting the system to R134 coolant.  
Does anyone have experience with these products?  Any recommendations?

Thanks in advance,
Doc