David, I thought of the Moka pots after I posted. It is a good portable coffee maker, but it really can't be called espresso. The Handpresso and Mypressi both use similar pressure as a standard espresso machine. With those portable machines, you could probably expect a really decent shot of espresso.
Handpresso is releasing a new version of their machine that uses ground coffee instead of the ESE pods. I emailed them yesterday since the site shows the new version, but its not available for sale in their "buy" tab. It will be available for sale in June.
I think I'll buy the new version of the Handpresso. In terms of simplicity, the Handpresso that uses ground coffee makes the most sense. The whole idea of using pods kills the deal for me. The whole reason that I make French Press coffee on the trail is that all I have to do is pack up my stuff that I have in the house. I don't have to go out and buy new beans or worry about keeping pods around. So in a sense, with the new Handpresso, all I'd have to do is pack up some beans and my grinder and I'm ready to go.
The big downside to the Mypressi is that it adds another level of complexity since it uses CO2 cartridges. I remember when I was a kid looking at pellet guns. I chose a single pump pellet gun instead of one that used CO2 cartridges.