The Changelog is the official changelog, & is used as is from the PA announcement thread.
Its said 'wait till spring', but the real meaning is this: Wait for a very long time.
That's the perspective of a GNexus owner.
Now we, at S3 end, have some more exposure to the bitter truths of Sammy world.
There's crap floating all around.
I love my S3. Its the most powerful smartphone in the world, at least it was at the time of my purchase.
But thanks to Samsung, the prospect of ever buying a Samsung device, is grossly repulsive to me now.
Samsung has done its best, & come up with the Official JB firmware, which is B.S compared to latest AOSP JB revisions. There should be lot of new things at play: Vsync, Triple Buffering etc, but they aren't.
If you've watched the comparison video, you'll see that most of the times, Stock ICS is faster than Stock JB. This isn't performance talk, this is speed, smoothness, response, & acceleration talk.
(Not the same thing. Super smooth phone won't necessarily give you awesome performance of game like GTA 3, but high config will, irrespective of general smoothness of UI)
The device isn't utilizing its hardware to its full potential. Hell, not even to its half potential probably. There're so many missing links in between the sources, which are filled up by developers, stumbling in the dark.
To be concise, we're stuck. Stuck with the sammy limitations, & its never gonna go away. There's no resource, or documentation, to make it go away.
The PA you run, is the smoothest possible form of any ROM that you can run on S3. Yes, their might be equally smooth ROMs, but not smoother.
The answer to your question, yes its controversial, but here's the tiebreaker:
What I say, stands... unfortunately. We may never be able to be even close to Nexus speed/smoothness.
Quad core is unnecessary. Dual is more than powerful enough to handle it all, as proved by GNexus. And most of our apps still do not utilize the threaded multi-cores. Most use single core, a few tax both cores.
My suggestion: Unless the unlikely event of Samsung opening up & supporting every thing, bit, hardware, source etc...
Stay away from it in the future.