Depends very much on the hosts and network; but yeah, I have two different aliases for one host in such cases: one for data-trafficking, another for latency-sensitive applications (e.g. interactive jobs). This way, there are two SSH connections up, and while they're still contending for the link, it's quite an usable setup (in other words, I'm letting the TCP/IP stack handle the contention, rather than the SSH multiplexer).