Finally i decided to use Nginx in my Flarum testing server and exists some issues. The first one is a little mistake from official Nginx server configuration block at http://flarum.org/docs/installation/ that will throw a warning:
nginx: [warn] duplicate MIME type "text/html" in /etc/nginx/sites-enabled/forum:68
nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
nginx: configuration file /etc/nginx/nginx.conf test is successful
It happens becasue MIME type
text/html is compressed by default and don't needs to be explicity declared into
gzip_types section. You can remove that MIME type from the config block and issue solved.
Source doc: http://nginx.org/en/docs/http/ngx_http_gzip_module.html#gzip_types
I report here because i don't know if this should be reported at Github...
Exists at least one more issue that needs to be tested more in depth to reach a final solution. Soon as possible i will report it and how to solve it.