Updating modules with drush without breaking SVN?
because running these commands does indeed get the newer version, but it destroys the SVN data folder in the process, leaving me with "! module/file.php"


I'm running Drush 4.4 and this does not appear to be the case for me. Running drush upc or drush up keeps your .svn directories intact. You can svn status to review the changes to the modules. New files are indicated by ? and removed files are indicated by !. 

Test your site's functionality. Once you are satisfied that the modules are still working correctly, you can then svn add/remove with a snippet such as the following:

add:

svn status | grep '^\?' | cut -c8- | while read f; do svn add "$f"; done


remove:

svn status | grep '^\!' | cut -c8- | while read f; do svn rm "$f"; done