I find, with either BearShare or Shareaza, many many people sharing a very wide variety of .ogg files...
.ape is also out there in ever-growing numbers...
As far as .mp3 is concerned for your specific intensions...
If I understand you correctly you are talking about making available some rare material. If that is the case, and it was me doing it (as I actually have
), I would ONLY use 320kbps for the .mp3s... Why ? Because there is no point in starting off anywhere but with the highest quality... In fact, I would do them .mp3 vbr at the highest level.
Let the 'others' screw up the sound even more than .mp3 does anyway !!! Someone else wants a smaller file, that's their problem !
It would be nice to know that you did your best in not only presenting 'new' material to the sharing world but, that it was done with quality in mind as well.