So out of box install of Ubuntu 12.04 now includes mp3 encoding (as well as decoding using fluendo decoder).
But theres this issue with VBR encoding (which is set in default gstreamer pipeline for mp3 encoding). And yes its been open just over 6 years!
Still I learnt about a handy tool called "mp3check" (and id3v2), exactly the kind of toold I'd been looking after for ages.
Of course the correct solution is to use a decent cdripper like the cli-based abcde.