Socket.io with PM2 Cluster in production - websocket vs sticky session

I'm a bit confused. I'm using socket.io on my NodeJS Server using a simple:

const server = http.createServer(app);
const io = socketIo();
io.attach(server);
io.adapter(redisAdapter(process.env.REDISCLOUD_URL));
server.listen(3000)

Now I clustered my server process using PM2 Cluster option.

My nginx configuration is straight forward as follows:

location / {
                proxy_pass http://localhost:5030;
                proxy_http_version 1.1;
                proxy_set_header Upgrade $http_upgrade;
                proxy_set_header Connection 'upgrade';
                proxy_set_header Host $host;
                proxy_cache_bypass $http_upgrade;
        }

Should I also add websocket transport instead of the normal http polling?

const server = http.createServer(app);
const io = socketIo();
io.attach(server, {
   transports: [ 'websocket' ]
});
io.adapter(redisAdapter(process.env.REDISCLOUD_URL));
server.listen(3000)

In socket.io website they recommend against it and they suggest instead to balance load between nodes using upstream in the nginx.conf file with sticky session as follows:

upstream nodes {
    # enable sticky session based on IP
    ip_hash;

    server app01:3000;
    server app02:3000;
    server app03:3000;
  }

But my I don't have app01, app02 and app03. I have my PM2 processes, but they all reside on the same localhost:5030 address. So am I left only with the choice of enabling websocket transport and losing the fallback option for long-polling?