Granted I’m a noob at VBR, but I did a quick test on a file I recently produced for a client. At a CBR of 128, the file was about 25MB. I exported a .wav from Hindenburg Journalist Pro (as it does not support VBR as an export option) and used Audacity to create a new MP3 using VBR. I used “level 3" which (if I remember correctly) allowed it to go as high as 192 (to stay with your example).
The resulting file was 37MB. 0_O
A sample size of one isn’t close to scientific, but the initial results (PITA to change my workflow not withstanding) don’t bode well. Thoughts? Suggestions of a different VBR setting to get higher quality audio at a lower file size, even if those gains/reductions are incremental?