I prefer Lame 3.98.4 over later versions as I find that it introduces less artifacting to my ears at 128kbps CBR (Haven't ABX'd though)
I've recently looked through the Lame changelogs and it says that version 3.99 made all modes use the same psychoacoustic algo as VBR New, due to one user's sample that sounded garbled in CBR and -q3.
Has anyone done an ABX to confirm that the sound quality is any different?
I too, have the impression that Lame's CBR quality regressed in newer version. However, I haven't done sufficient testing to claim this perception as fact.
Some circumstantial evidence that current Lame isn't doing particularly great in low-bitrate CBR mode I posted over at https://hydrogenaud.io/index.php/topic,123331.msg1020215.html#msg1020215