Xfce 4.12 to be released next week!

[Valtam]

XFCE 4.12 is like a freshly-baked dessert - one that needs to cool a little in the breeze before it's sliced and served.

One of the best analogies I've heard for integrating new packages to an existing system.
I would expect 4.12 to show up in 15.04 or even 16.04 and since we base off LTS, you're not likely to see 4.12 in LL until mid 2016. If you like to drink your wine fresh off the vines go for it, personally I prefer a matured vino.