I've been using Ext 2.0 for so long in a multiplayer browser based game. At that time, there is no Ext.Direct then I must created one on my own.
It works well till now but I still want some thing built-in and more standard.
So I've take a look at Ext.Direct, it's small and good but it seems missing some things.
As you know, polling method stresses server so much. In a high traffic website, reducing number of call to server is a must. But Ext.Direct seems to not concern that.
So I suppose that you would implement a message queue at client-side and to transport them all at once. it would reduce calls much.
You can take a look at my game site at: Yugiohnetwork