That's a good question. I'm going to try first with Hetzner and measure latencies from different places; if this becomes an issue, I'll definitely consider complementing the infrastructure from elsewhere. But I'd rather start simple.

I currently run a web service from North American servers and the performance here in Europe is quite good. I think this experience - very, very limited - gives me confidence that the wires across the world are good enough, provided your data center is close to the main pipes.