Just a quick follow up....try_files is definitely nicer and more concise, but i realized my error and want to make it obvious here to anyone who might do the same: be very careful about using relative vs absolute symbolic links.

file -> a/bar.png

is very different (and won't work) than

file -> /var/www/path/to/a/bar.png

Thanks again Mike and Igor, really appreciate sticking with me on this.