Vhost on port 80 (http) and port 443 (https). Has anyone disabled port 80 when running ssl?

So, as the above title asks,
if a virtual server is running SSL (port 443), is it possible to disable port 80 and also that vhost?

If so, does this save any system resource usage?

what are the implications of disabling vhost on port 80? (my assumption is that if something goes wrong with SSL there is no fallback without a bit of stuffing around re-enabling vhost on port 80)

Is there security advantages in this, or is a redirect in .htaccess, for example, the best compromise?