I you are going to have a smartphone (Android or iOS), consider getting an SE; if not Explorer is a better option. As everyone else mentioned, reading the messages, and even more composing them on the little keyboard is a pain. Also consider creating pre-canned messages that you can select. You don't want to spend time on composing it, when you really need to communicate quickly.
If i were you, I would setup someone on shore (family, close friend) who would be the main coordinator in case of emergency. I have no experience with Delorme Emergency Centre, but I know from personal experience that one can reasonably easily coordinate (or at least trigger) a search and rescue operation from home, even if it is at the other end of the globe, if one has access to InReach messaging. And that person has an advantage - he can communicate with any S/R operations, regardless of the country (though some language skills would be handy).
That central contact can also provide tracking information to you , if needed (e.g. weather forecast). You don't need much text to pass along the wind speed and direction for the next few periods.
Marek