It depends how you work.
I have to leave all my previous installs in as I start projects with midi files. You can import them but that's too much work. I right click on my midi files and use the "Open with" command and select Sonar. It always goes to the first version you installed on your current OS install. I unistalled it and I could not use that command. So I put it back.
The reason I use the "Open with" command is that importing midi files does not import all the settings a midi file contains like, tempo, key, markers and other things like that. The "open with" command does that.