I'm not sure how that is supposed to work. You would have to rewrite every webapp so that it's data can be protected by sandstorm. Which seems hugely impractical. And as long as the webapp has access to it compromising it will compromise the data.
That's just marketing bullshit. Unless the API is magic (and I don't mean advanced technology "magic" but Harry Potter "magic") it has no way of knowing what the application is allowed to send or not and therefor cannot filter. It's like saying it cannot leak data because it has to use HTTP.
Host authentication is a job of SSL though. So you should simply not log-in on a website if it cannot be verified that it is actually Paypal. This holds for both SQRL and passwords and seems to be an independent issue.
It also applies to this case because the ssh server is supplied by the website.
In short: The protocol is not even remotely thought through. It is incomplete and cannot work the way it is described.
I wonder if it is theoretically impossible to create a protocol that punishes cheating when the cheating occurs outside the system (when the physical goods change hands).
And even if it isn't you would also somehow have to consider the fact that things get lost or damaged in the mail and assign blame to one party on the protocol level.
I intentionally did not try to answer the question myself because I assume there are people who are much more familiar with the details of the XMPP protocol and much more suited to making a comparison.
So fuck you and your shitty rtfm answer. I can't just read that and find out myself. Just like a bunch of satellite images would not answer my question what the weather will be like tomorrow.
I would like to know how this is different from jabber/xmpp and how likely it is that these differences are worthwhile. They say their API is more "pragmatic" and writing a full-blown XMPP client certainly is very tricky but I wonder if improving the way XMPP works wouldn't ultimately create a better result. After all, a lot of thought and experience has by now gone into it.