I never deployed a meteor app before. I never used such system of servos. I don't understand how it works. I always used plain shared hostings. Php etc.
My question is: How much traffic can a 396mb servo can handle? I mean, I know it depends on the app but is there any reference, any clue for understanding what I may need?
On
It varies greatly depending on your app, and there is no silver bullet here. The best you can do is to monitor and scale accordingly. Using Kadira might help you a lot with that.
For what it's worth, I deployed a Meteor app on a 396MB Modulus servo a while ago, and it easily handled over a hundred or so simultaneous users even without Mongo oplog tailing.
a typical 396MB servo can handle approximately 400 concurrent connections for a typical meteor app on the Modulus platform.
full disclosure: I am a Modulus employee.