Same as any non-LEO satellite link (probably like, O(700 ms) latency? About the same as our experiments in Greenland...). Not great, but fine for administration and light vimming. The worst was when I had to update some py2 to py3 code after a system was updated, and there was no way to test except on the South Pole machine. The places where bytes vs. strings bite you when dealing with serial devices are plentiful...
This stuff is always so fascinating to me. I remember I was on a plane once and I had done a code deploy before getting on the flight, then remembered I forgot to upload the necessary files to the k8s cluster. There's no way I had enough bandwidth on a plane to get the files on the cluster. So I tried ssh-ing to my home machine and doing it from there -- nope, SSH is blocked on the stupid in-flight Wifi. So I went on DigitalOcean, got a $4 instance, and used the web interface to SSH into my home machine, and then from the home machine uploaded the files to the cluster. The latency was hilariously slow, I think over 1 second, but it worked!
I was thinking about the route those packets were taking - from my computer to the plane router, up to a satellite, down to the DO data center in NY, from there to my home in NJ, then to the K8s cluster in NY, and then all the way back around. When you put it that way, one second per character isn't that bad.
With mosh you can even resume connections after disconnecting but without losing interaction with the target machine as it happens under SSH. Also, it will use far less bandwidth. I tried it with 2G/ISDN-DSL like speeds and it worked great. And you can keep using tmux just in case.
On the "caveats", you need UTF8 support in the client machine, but today that's granted.
I'm sure there are some advantages, but I couldn't quickly figure out how to get it running with the various jump hosts required (and I also often use port forwarding...). Just having tmux on the other side gets me most of the advantages, I think...
Well, on port fwd, maybe if you forward the mosh server port would work. If you use SSH itself as a tunnel, the setup it's far complex, as mosh is just a remote shell.
Still, mosh curb-stomps ssh on latency, input guesssing, data saving and bandwith usage.
Using that over 2G was a literal black/white difference compared to SSH which was nearly impossible to connect and the latency was unbearable. Under mosh I could chat, email, nntp (they still are some good newsgroups), IM over jabber/telegram, read news over RSS, code in C/TCL (jimsh) and read the docs with links, among reading books (novels and essays) with some CLI epub reading script.
Yes, I also used tmux on the remote machine too, mosh+tmux work great with each other. Albeit mosh resumes a potentially lost/dropped connection just fine (even without a running remote tmux/screen), I think tmux itself would send less data over the wire.
