You don't need to upgrade for the sound, the BTR3 is powerful enough to drive any IEM. Update if you need a feature that yours doesn't have.

Had a BTR5, now I have a Qudelix 5k. Sound is the same (as it should be ffs), but the experience is much better, the app is constantly upgraded, with new features, lots of options, eq working with USB/BT is great. Really couldn't be happier