We paused on it while we started working on Metal on the Mac (which is always deferred, so iOS will just reap the rewards).
We are merging much of the code from a Metal development branch into the main branch of UE4, but it’s not clear if it’s going to be working for 4.10 or not. Certainly we are focusing on Mac right now, but trying to keep iOS MRT stuff as functional as it was.
Deferred rendering is a method that allows for our high end rendering features (basically, it’s the desktop renderer). However, it’s not actually well suited to the Tiled GPUs that are in all iOS devices, and many mobile devices in general. There is one main weakness of Tiled GPUs, which is many rendering passes where the render targets need to go out to memory. Deferred rendering has dozens of passes, forward rendering only has a few.
So, while we are working on the feature set for iOS, it’s not going to be optimized very well for awhile, or until the hardware is fast enough to make it work well enough.
Hope this helps!