If I remember correctly, we've done a few modifications to the Embree version we are using in Corona, so it's not vanilla 2.11. We'll have to wait for Ondra as he's the one who's been digging in Embree code fixing few problems that we had.
2nd - i believe Corona 1.3 had the best memory and resource management against of newbies.
Well, there were a lot more changes between 1.3 and 1.5 (even 1.4) than just switching to newer Embree :) Actually I did few quick tests a while ago and 1.4 used less memory than 1.3 on the same scenes.
Corona 1.6 is "done" and now we are waiting for the release candidate to release. Any Day now it will be pushed with the 1.6 update.
The new reworked DR will require a lot of testing both internally and in the field. We also probably wouldn't want 1.6 to be "just new DR" and we'll add few more features on top of that (there are already some minor features, bugfixes and optimizations waiting for next daily). The current plan looks something like this:
- First 1.6 daily probably sometime next week
- 1.6 dailies until the end of the year
- Few days off on Christmas not having to worry about fixing bugs in RCs
- First RC in mid-January
- 1.6 release at the end of January or in the first half of February
But we don't want (and can't) commit to any specific dates. Software development is not entirely deterministic process and there are always lots of unknowns.
One of our main goals for 1.6 is also to do lots of internal code refactoring and cleanup which will allow easier implementation of new features and optimizations. My personal pet project is trying to lower the memory consumption of frame buffer and I certainly hope to be able to finish that in time for the 1.6 release :)