There is some discussion in the 300 vs 100 poll thread.
http://www.zpost.com/forums/showthread.php?t=813623
It sounds like you have a handle on the basic differences....
100s will no doubt be more free flowing but will be louder and suppress rasp less
300s are less free flowing not quite as loud but will suppress rasp better.
300s will also have a better chance of compliance with testing and a better chance of no SEL.
For my own choice; less rasp is a big plus, and I would like no SEL