Yeah, the abstraction was very leaky, and it was too easy to end up with megabytes of ViewState going back and forth, or a screen refresh on every button press.

Yeah, the abstraction was very leaky, and it was too easy to end up with megabytes of ViewState going back and forth, or a screen refresh on every button press. React, and Om built on top of it, seem very interesting. They also seem to be built on abstractions that that get out of your way while guaranteeing good performance.