IMHO, you may change the new controller under below situation;
1. old controller breakdown,
2. intend to get another new one to pair up your current one to form a master and slave function.
3. want to try new wave function (NTM, and TSM) which I feel it's quite useful .
if you feel the original function is sufficient for your liking and coral is growing healthy then dun waste the $$$ hor .