Still on 314.22 here too. I've read tons of issues in many forums (including Nvidia own forum!) for anything 32X.XX, especially for 320.18, which apparently can kill your card under some circumstances (Google it).
Also read somewhere that a major fork in the developer code is supposed to be merged back in the official driver for 330.XX or 340.XX series, I don't remember. My guess is it's for OpenCL 1.2, OpenGL 4.4 and some other new stuff. Could we have a DirectX 11.2 bonus as well? (I don't even know if Kepler is able to support DirectX 11.2 features in hardware)
I currently have no incentive to move beyond 314.22, stability VS performance is great. I'll wait for 330.XX and up to enjoy a major performance and feature boost in one big jump...and hope it's stable.