Hello,
My name is Jesse Savary and I'm a software developer with 8 years of experience, including 3 with Node.js. I have a deep understanding and working knowledge of every technology you have listed. I frequently use Express, MongoDB, and Sock.js. I'm also a bit of a speed freak when it comes to performance, so there's no worries there.
As for promises, I've used both Bluebird and Q. I prefer Bluebird as it a bit more straightforward but can use Q (or another solution) if you'd like.
I have a few questions regarding your application and would love for you to get back to me.
Looking forward to hearing from you,
Jesse Savary