We got the small business version and were quiet disappointed. The thing that really upset me about this plugin is that it won't allow you to customize the functionality. Read the licensing carefully. Only 1 file is open source and if you need to change one little thing beyond the settings menu, well you are out of luck.
They even go so far as to hide their code somehow, which makes me suspect that they are using external scripts. And what happens if their server's go down? Will the plugin continue to work?