Does the physical location of a server matter for high-throughput use cases? If a client is downloading large files using all its available bandwith, is the download time noticeably better if the server is close to the client?
For downloads high RTT can be mitigated by a congestion control that ignores constant packet-loss rates (which are common for high-rtt paths). Other tricks that you can try: fq+pacing and newer kernels with more sophisticated recovery heuristics.