The latest version of VLC Player was the culpret.

I play the song in sonar and it's just right.
I make an MP3 the way I have always done and it's comes out super-sibilence. (maybe not all trax but definitely the vox and cymbles)
My MP3 setup=
Export Audio
entire mix (I also tried out to "main")
stereo
what you hear
everything checked but 64 bit.
source Br800

https://dl.dropbox.com/u/24683934/YGC%20sib.jpg
I thought I had this down.

What bit-rate are you exporting to? Sounds like you need to bump-up your bit-rate.
 
EDIT: OK, I just looked at your image and see you are exporting to 128 kbps.  That's pretty low, bump it up to at least 192 kbps or higher, and that horrible sizzly top end should be better.