I wanted to provide some information on why Lion was set as the minimum requirement for Mactracker 7.
My intent was to support Snow Leopard. When I moved version 7 to the Cocoa framework I encountered some stability issues with 10.6. Moving from a Carbon base was necessary for Retina display support.
I chose to release version 7 with the Lion requirement while I work to resolve the stability issues with Snow Leopard.