The bottleneck likely isn't the server here, but geolocation. He has 3 Digital Ocean socket servers in three regions. A single dedicated server will only be in one region. For latency-sensitive applications like realtime games, having servers close to your users is a must.

But can I get 3 dedis in 3 data centers? I'd like to have that lest user experience suffers. I effectively get that with my setup.

Maybe one day when I need it, and certainly evaluating at any point.