Hey there!
Awesome mod! Really! But I already got used to JABBA/Factorization functionality and tried to set "B:invertShift=true". But the Shift behavior seems to be stayed the same. I still have to Shift-click for getting a whole stack instead of just regular right-click.
My current version is 1.3.7.

Could you try 1.4.0-alpha2? http://minecraft.curseforge.com/mc-mods/223852-storage-drawers/files/2235914

I couldn't reproduce this when I tested it. invertShift seems fine. Have you checked its state in the options GUI?

Just tried it in singleplayer and all works as expected. Is this a server-wide config?
--- EDIT: ---
Confirmed. I thought this thing's needed in client only, sorry :)

Well, this setting really SHOULD be client-only. I checked in a change, that will appear in 1.4.0, that should fix it.