i'm debating whether to symlink the albums dir to an albums dir outside of the webroot / or symlinking the content from an albums dir as this would allow me to have multiple installations across different sites without reuploading the content?

ie. i have albums outside webroot with all the content in, and any content that i want to appear in the gallery for the site, i just add symlink to the content in the albums dir for that installation. would that suffice? it could save gb's of duplicate content!

So you basically want to share the same album folder and its albums with several zp installs? I guess that should be possible, since Zenphoto is file system based. I am not sure if that has been tried before (and I don't know anything about symlinking I have to admit).

I see no issues with the concept. Zenphoto shouldn't know/care about the fact that it's symlinked as log as you don't move the folders all the time. For what you'd like to do I'd say this is an excellent idea. I'm personally a huge fan of symlinking, it's how I map all my local webhost folders on my PC for testing without having to traverse through my root structure all the time. I say if you're on a Linux server you might as well take advantage of the benefits. Just make sure you never get accidentally migrated to a windows machine