Can I really not switch my existing VM from Apache to Nginx?

Reading the article about using Virtualmin with Nginx, it says: only change to Nginx when no websites have been added to the server yet’.

I have a webserver with like 5 sites on it and it is totally not peak resistent. It can handle like maybe 30 concurent visitors, which is not enough. So I did a test on a new server with Nginx, and it performs way, way better.

I’d rather not go through all the trouble moving those Magento stores to a new (Nginx) server.

So the question is: is there a way to safely switch from Apache to Nginx on an existing environment?