I think that most people that have lots of experience using Node would say that it is stable enough for the most part (that's what I tend to read anyway, big gr

I think that most people that have lots of experience using Node would say that it is stable enough for the most part (that's what I tend to read anyway, big grain of salt with that). Cross-platform compatibility is much, much better than it was in the distant past. It will be the idea and not the technology you choose that will determine whether or not it becomes the 'next Twitter', as long as it is developed soundly. It shouldn't really matter. If you did end up scaling up before the final kinks are worked out of Node.JS and commonly used libraries, then like you say: Just write it in Python over the weekend and see if you can do better.