The Korg controller keyboard is just like any other controller keyboard, USB etc.
The Legacy software is just bundled with the keyboard and is independent of the keyboard. just a really nice thing Korg threw in.
They work independently of each other.
I have the Legacy M1 software - it's so so nice. The bundle is to expensive with keyboard or just the bundle for me right now.
I am thinking of just paying for the Legacy Wavestation and the effects products as I want those and am not really interested in the analog plugins. $49 +$20 doesn't seem that bad for everything included.
There are so many banks for these synths on the internet the amount of sounds is just incredible. for M1 and Wavestation I have found about 8000 sounds that were once purchased hardware cards and companies just threw the sounds on the web free - can even purchase some add on banks still from some companies.
I thought of Legacy as old maybe useful but have found I use these all the time now. I use them more than Rapture or Zeta from Cakewalk.
glad they are 64 bit now - though the 32bit worked just fine in Sonar x64 with no issues.
if your on the fence at all just take the plunge - totally worth it and there are many sounds to be had that are not throw away sounds.