Looks suspiciously similar to my Amiko Pay, except that the commit conditions are different. I'll have to dive into the details of their proposal to figure out whether this is an improvement or not. Their proposal also seems to require additional Bitcoin scripting functions, but possibly less intrusive ones than my proposal. I'm also interested in to what degree a useful implementation of this can be made without those scripting extensions (presumably that would be less "trust-free").

And of course: I'll think about whether their commit conditions leave any vulnerabilities / abuse modes. It can be really hard to get these things 100% right.