Just published my Ajax library. It is very much like jQuery. In fact it is a micro library I built so I would not need to load up jQuery. It comes bundled with FN_Deferred. I admit it is not as full featured as FN_Deferred, but it is very much like jQuery Ajax, and could be the replacement you are looking for.

Go micro, Go Fast.

https://github.com/josephtveter/FN_Ajax