Thanks for the feedback, Stream Recorder.
I think for the most part, you are confirming what I suspected. I am using
StreamRipper for recording and
MP3DirectCut for trimming, for the very reasons you mentioned.
It seems reasonable to me that decoding an mp3 stream and then re-encoding it is going to degrade the audio, which you don't want to do when your starting point is already as weak as 128kbps.
Even if the
Audacity .auf format is lossless, it is still doing no better than capturing all the information in the streamed mp3. And in order to play the file captured by Audacity, I could code it to FLAC or APE to make it playable on most players, as you suggested. I wonder how the file size would turn out. I might have to try this just to see. In any case, I don't think I want to recompress back to an mp3, since that would no doubt degrade the audio relative to the original mp3.
Thanks, again, for helping me out.