The app I want to build would be data driven. I want it to be as fast as possible (it will have to plot graphs) and I thought I made a good choice with my current stack. The big difficulty is understanding where each library/framework shines, how to couple it with the others and when two frameworks have some overlapping functionality, which one to keep.
The reason I didn't go with Meteor at first was that I didn't really understand how everything fits together. I needed to build a stack block by block. But that was three weeks ago, I will definitely read more about Meteor and maybe give it a try.
One thing's sure, I have to make up my mind sometime soon or else I'll never have a prototype!
Unless you're going to be wildly successful the moment you launch, you're better off picking one stack that you understand, creating a working version, then iterating to improve on it. If you try to do it perfectly or make it as fast as possible from the start you may never finish - and you'll never be able to test your idea.
I've tried something similar, that is Rails + Ember.js, and I find using Meteor.js easier.