You'd be best to contact David Sloane from Pro Landscape and check with him on the similarity of functions. I can see it is a worthwhile upgrade from version 11, which I am now using. It looks like it only adds features and benefits to 11 and doesn't change the functionality. Have you checked out their website for the information? I received an email today quoting the prices for the upgrade to previous versions. If you need the information I would be happy to post it.