2.4ghz vs. 5.7ghz Wireless Broadband?

As a bit of a follow-up to our previous discussion on wireless broadband options, Linxx asks: "I work for a company in Yuma, Arizona that offers Wireless Internet access. We cover a large area that extends into Southern California as well as Mexico. We currently use 2.4ghz equipment to do this. We are looking into using 5.7ghz equipment to feed our access points and the rebroadcast at at 2.4ghz. We hope to releive some interferance issues. What I want to know is if anyone has actually compared the two, and if so what kind of results were produced."