Well I don't know if this will help.. I just had a system installed and the guys were very imformative.. This is what they told me.. The puron might be more valuable if you are planning to keep the house for a long time, otherwise the r-22 is cheaper to install but, the service might be more expensive in the long run with epa standards and govt raising the prices on r-22. Although there is no conversion kit for the r-22 to puron right now there might be later. (they have have them now for cars) So in short it might be a better investment for the puron if you plan to keep the house. I voted for the r-22 since I plan on selling the house in a few years, hoping that it won't backfire on me when I try to sell the house.