I tried to post this yesterday morning, but TeeEss's server was playing up....
Anyway, the answer is iTunes-LAME works great. A four-minute track took about 40 seconds to convert (iMac g5 running Tiger - newer machines should be faster). The Best of Chet Atkins (17 songs, 1.1 hours) in a few seconds under 14 minutes. I also converted nine tracks from Bob Seger's Against the Wind.
The Seger one came into the conversion folder properly numbered and in the right order. However, the program cached tracks on the Atkins one as it was converting and managed to change the playing order. Almost completely reversed, but not quite. Could be a bit irritating for some people.
iTunes original mp3 folder