Re: Members can only view thumbs not images...
I thought it had been added to RC2, but maybe that was aftewards as a hack. When you view a usergroups permissions in the Gallery AdminCP, it should be the permission right under Can View Images. If it's not there, it must have been added after RC2 was released.
If you don't have that option, then I'm not sure why they wouldn't be able to view the full size image.