... well that was scary but i managed to upgrade..
writing it out in case it helps someone else ..
i uploaded all the 3.5.0 files overtop of my existing 3.4.7 files,
then ran into this problem:
http://www.viart.com/forum.php?sf=&sw=This+encoded+file+is+corrupted
which was solved by forcing binary upload of the /include folder (i've never heard people doing this??)
as well as redownloading my license.php file from viart and uploading it to the /includes folder (guess it gets overwritten by the 3.5.0 file package?)
then i ran into this problem
http://www.viart.com/forum_topic.php?thread_id=1487&page=1#message_form
which was solved by manually going to xxx/store/admin/admin_upgrade.php and upgrading the db this way.
It's ridiculous that upgrade instructions weren't included in the release... I've been working with php/db/etc scripts for 7 years and have never seen an upgrade process as bad as this.
.. not to mention all my custom template changes will have to manually ported into the new 3.5.0 files (will be using the /templates/sitename trick from now on)