I can't find this listed anywhere, so I figured I'd publish it.
My Khyber mechanic rogue is a half-elf and took the arti dilettante feat in order to get proficiency with repeating crossbows.
Since the EP, the feat apparently no longer gives the proficiencies, only the scroll UMD bonus.
With the improvement enhancements only adding 1 caster level each, arti dill is now (imo) completely useless.
This is not in the release notes, so I'm not sure if it's on purpose or just a side-effect of something else.