I gave up with 2.6.x - it is unusable for everyday usage and only annoys me with the not well thought out usage and strangeness. Back with 2.5 branch.
The only thing that could make me use 2.6.x soon would be a real cleanup on the x264 option, reduce to one page, offer "--preset" and "--tune" and "additional options command line", + encoding mode and quality + aspect ratio. A bit like the x264vfw version.
If would INCREASE the quality of the encoding since quite some options used by --tune are nowhere to be found on the 2.5 x264 GUI.
In fact --preset + --tune are so well tuned that my original overly sick long command line for old x264 versions got down to four options.