I think you should not use different versions of Artisteer, you should always use the newest version that you own. The plugin only works for Artisteer 4, 4.1 and 4.2. You cannot install multiple versions of our plugin into Artisteer, so you should use the newest Artisteer and the newest plugin for best results.
At any given time I'm only interested in making sure things work with the latest version of mojoPortal, the latest version of Artisteer and the latest version of our plugin. I am not interested in supporting older versions. I recommend people stay up to date with the latest versions of all 3 products.