The good news is if you already have MAP even if only inside C3D you do not need to choose between the two to start 'doing' GIS with the flavor of MAP that you have.
Later; should you find that MAP just isn't working for you there is a tool that will allow you to export it all mostly intact into any other GIS application.
I say this, firstly to let you work with what you have. Secondly you may have data that you want to use for GIS purposes, however that data most likely needs to be groomed in some manner prior to being added to ANY GIS database. This approach will allow you to move forward with your GIS implementation most efficiently.