Quite interesting. Is the Vert.x API compatible with CommonJS and/or Node modules? If not, I think it will suffer from the same chicken/egg problem that WebOS had with apps.
Node is a joy to use because of the NPM, and all the available libraries. I'd hate to lose that.
That said, so long as it has a solid websocket api, and I can do routing in it like I would express, I'd give this framework a shot
Maven's not bad at all (from a consumption perspective--from a dev perspective, it's a bit of a pain in the ass), and it looks like pretty much any Java library that doesn't do anything too insane should work just fine. (Disclaimer: never used vert.x myself, but I did a quick scan of the code.)
However, it's unlikely that node modules will work as is with Vert.x, since the API is different. (Unless someone writes a translation layer)