If we broaden the discussion to any type of JS framework (not jut the ones for SPAs), it seems every other day a new JS tool or framework is born. Do you often get the feeling you can't keep up? Like you're in a room where everyone is shouting for your attention and you can't really understand anyone? Sometimes, it feels like the Wild West. Maybe it's better to just wait it out and see which technologies remain after the noise settles down.
That could be a rational choice. There's nothing wrong with it. I too often have doubts on whether the time I'm investing in learning something is worth it. I recently spent two weeks trying to get a Mimosa skeleton working on NodeJS in Azure. NodeJS and Azure are here to stay, but shouldn't I have looked into Yeoman and/or Grunt instead of Mimosa? Do they even do the same? I don't know!
On the other hand, this time isn't wasted, even if the technology you chose is discontinued in the future (unless you're going for commercial production-ready stuff in which case you should probably choose wisely).
And finally, if you're still the careful type, some clear leaders are emerging. NodeJS is here to stay. Angular has gained enormous traction, this is no longer 'a small interesting experiment'. RequireJS is being used just about everywhere. Bower is very popular.
All that being said, I have explored Durandal, but to be honest, I will now be taking a serious look at Angular. It seems to be getting more traction and has a larger community. Just don't think you have wasted your time if you learnt a framework that didn't really take off.