219xx is most certainly NOT totally identical to 217xx, but the base os code is from this branch, this is why they appear very similar
Most of the UI changes in 219xx are very subtle, and almost all have already made their way into 218xx
Combination of older base os code and the same UI features in 218xx make it not really worth using at the moment..
Only an interesting branch to follow to see what might filter down once it's stable
Just got back from my trip, catching up on posts and pm's and emails and such