Hi Steen and Meo
situation is not so bad with 3.14.y as you say. Branch was created 8 month ago, but there are updated which are one month old only.
You are right, kernel development effort is focusing on Raspbian stable 3.12.y kernel and it is the most advenced in terms of Raspberry, while 3.17.y and 3.18.y are experimentals for example used to develop device tree or other features, but much behind on audio SoC support for example or has issues with wifi device support. Now as I see 3.17.y/3.18.y can't be used as a stable kernel in near future for us. We can make a decision to be conservative and use the mainstream Raspberry kernel, 3.12.y. I will make a 3.12.35 kernel and see how it goes.
Béla