Yep, know that feeling.
Perhaps my best advise is to pose a question; what is it about sound that does something for you over what the rest of what RP offers?
I long ago came to the realisation that RP's sound would always be second fiddle to LokSound and SoundTraxx because they keep putting in the development effort and, as far as I know they don't just expect people to give them something (recorded sounds) to generate profit from for nothing. That said while I'm not heavily invested in RP I don't think I could be honest with myself and go back to DCC as it is today, and that has been sorely tested over the last few years but I'm still with RP.
Back to your dilemma, I don't know what speakers your using but quality speakers can do wonders, what's provided with many models ex factory are just junk and the sound chamber for it also junk. If your using what come's with the models you may like to get a quality unit from someone like Scale Sound Systems and test with it. Other than that there is nothing wrong with having DCC Loco's and RP Loco's, I believe that this is quite normal.
- Tim