drupal + authcache compression with nginx?

hello,
the authcache module suggest to turn on the drupal compression, but i allready have nginx compressing my files so would it be better to use drupal compression or nginx?

nginx config:
gzip on;
gzip_disable "MSIE [1-6]\.(?!.*SV1)";
gzip_comp_level 2;
gzip_proxied any;
gzip_types text/plain text/css application/x-javascript text/xml application/xml application/xml+rss text/javascript;