I've used Polymer.dart for browser game consiting mainly of simple windows. From that I can say the most important downside is the poor performance on mobile (e

I've used Polymer.dart for browser game consiting mainly of simple windows. From that I can say the most important downside is the poor performance on mobile (even with shady DOM). Despite that I'd probably still choose Polymer if I need browser framework because webcomponents encapsulation feels great from developer perspective.