Well, there is a whole thread dedicated to people discussing using other programs as well as Roon. Hmm, let me check. Yep, starting in '16 and still going…You and Roon: Monogamy or Polygamy?
As for using the programs, I have a ROCK server as well. Doesn’t stop me from using the other programs in addition. My music is both local to the Rock for Roon. And on a NAS, where JRiver installs point. Foobar is used mainly for odds and ends.