I must say that at the time of writing the new lib I thought that only Autobahn.js and wampy existed. This lib was born because of dependency hell and poor typescript compatibility of other libs. Also using rx is a very good fit for WAMP which other libraries (or so I thought) didn't support natively.
So yea I guess the distinguishing feature of this new lib is that it is both supporting typescript natively and is based on rxjs. But also that it contains almost only one dependency.
Greetings
Johan