Hi,
My first question is which Mobility Controllers do you have? Only 70xx and 72x0 are supported on ArubaOS8.x
1A Migrate from Master-Local to MCM+MC (option #3), you don't need a VMM/MM, but you loose a whole lot of kickass feature of ArubaOS8. And the MCM can't terminate AP's
1B Migrate from Master-local to Standalone controllers (option #2), same result as 1A, no license needed, no cool features
1C highly recommended!!! (Option #1) Get the MM in your design! And yes you need the license, but both controllers will become a MD and both can be in a cluster. In option #3 the MCM (one controller) can;t terminated AP's so you might need an extra controller. Better buy a MM.
2 The migration tool will only work on the MM, better do a new install and get rid of old legacy config. Licenses can be on MM or the controllers. ArubaOS8 with MM will do 'central' licensing to have all the licenses available in the MM.