OK, thanks to everyone. I got the idea that I don't need to dump Legacy, and from all I heard I think there are still multiple reasons to keep it around.
However, I still have a question that is a little more clear now:
Whenever I do scan with my ScanSnap iX1500 and neither version of Evernote is open, it always opens up the Legacy version, not 10.22... Is there any simple way to determine which one opens when scanning?