RB is very reliable and has a lot of features that I like. The OF lacks a lot of basic features, but after doing a sound quality comparison between the OF and RB, I found the OF to be better than RB. As a result, I switched back to the OF. I only use RB when I need to use the recording features. Does RB sound bad? No not at all, but not as good as the OF IMHO. Using the same same songs in FLAC format, I compared the sound quality with the EQ's flat and special FX's off. I found in every case that the OF was lively, there was good instrument separation, stereo image was wide, the music sparkled, there was good proportion between lows, mid and highs. I had no need to EQ. On the other hand I found RB to be narrower in stereo image, a bit muddy with not as good instrument separation, the highs were slightly recessed in comparison and somewhat harsh, the sound was one-dimensional, flat, almost as though it was compressed (even though the limiter/compressor feature was off). I tried to play with the EQ and stereo image feature in RB to make it sound more like the OF, but no luck. In every attempt the EQ and stereo image features distorted the music and ruined each attempt.
I don't know if it is the RB implementation in the fuze that is the problem or Sandisk has done some very special processing of the sound in the OF that is not apparent. I do use RB in my Ipod Video 5.5g and it sounds really good with it, but I have not done an A|B comparison between the Ipod and the RB firmware yet.