woodelf druids shrink when mask is taken off, halflings get bigger (i tested this a while ago with a halfling next to me). i assume humans get smaller too. part of the problem might have to do with the fact that when you zone, you lose the magnification part of the buff, but i think the size increase stays (doors in RV block me when I am standing with mask on, even when i zone in with it on already).
as an example of what you can do with taking off mask and using a shrink pot I give you my buddy and me:
http://postimage.org/image/84ypv61qb/