Wait, over 50ms is high latency now? That's less than transatlantic traffic delays, for example. I think you have to be in the actually noticeable (say 250ms plus) range to count as high.

Not to sounds like a Monty Python skit, but 50ms really does seem like luxury to me :-). I guess to back up the OP's point, I regularly use vim over 250ms+ latency lines for hours on end. It's not fantastic, but it's definitely doable. You need to have your vim golf game up to par, though :-)

You know your latency is high when your mental model switches from vi(1) to ed(1).

If you use classic vi modes, I think vi/vim is much more forgiving over high latency than emacs, for some reason.