For HF emergency comms I'm pretty interested in the PSK31 mode. That's an ultra low speed digital mode (31 bits/sec) that uses even less bandwidth than CW. The speed was chosen to be just fast enough to keep up with moderately fast typing (40 wpm or so). The low bit rate means you can have text chat conversations with about 1/100th the power needed for voice conversations. So that 5 watt FT817 on PSK31 is like 500 watts voice. For emergency comms, text is if anything better than voice, since you can send stuff like GPS coordinates and it's all logged directly to the other person's computer.

I've thought for a while that someone should make an all-in-one PSK31 transceiver (maybe single band 20 meter) the size of an FT817, with a keyboard and display and all the modulation stuff all in the same waterproof box. It would be a no-operation-cost backup or substitute for a satellite phone, capable of communicating from the remotest areas as long as you could set up a reasonable antenna. The only drawback would be the text-only nature, but us computer users have gotten used to that.