I see where you are coming from. And I agree that it's a trade-off. But I think my point is, that from a usability point of view you simply have no other choic

I see where you are coming from. And I agree that it's a trade-off. But I think my point is, that from a usability point of view you simply have no other choice than having X codebases, one for each platform you want to be on, if you are not willing to compromise on usability. I don't know of anyone who tried themselves at the magical "write once, run anywhere" and delivered a consistently great user experience. Of course, it would be hyperbolic to say that the Khan Academy app has some huge usability flaws. It hasn't. But I'm mostly thinking about another example here: Facebook. They're a billion dollar web company and even they managed to majorly fuck their mobile apps up in terms of responsibility and general snappiness. They tried "write once, run anywhere" and failed. There was an article about Facebook's mobile technology on ReadWriteWeb some time ago: http://www.readwriteweb.com/mobile/2011/09/how-facebook-mobile-was-design.php http://www.readwriteweb.com/mobile/2011/09/how-facebook-mobi... (I hope this information isn't outdated already) HN discussion is here: http://news.ycombinator.com/item?id=3397872 http://news.ycombinator.com/item?id=3397872 I think empirical evidence shows that this is the wrong approach if you want to deliver a good user experience.