I've been playing a bit more with F2FS with an F2FS overlay.
It's seeming fairly resilient and performant. Using 1.2 of f2fs tools fsck seems to at least pretend to repair problems on sudden loss of power.
My own image is fairly heavily customised to do a very specific headless loginless task so is not suitable for general distribution (/etc/rc.local is a thousand of lines mess that copes with lots of different hardware configs. It's grown over the last 2 years & is well overdue a rewrite from scratch).
Having said that, if there is enough interest I would be willing to put a generic raspian image onto f2fs with an aufs overlay with the only customisation being "my" kernel, which is now up to 3.12.4 and make available an image of it suitable for deploying to a 4GB or bigger SD card.
I use a 3rd partition for the RW overlay as I need to persist changes over reboots, but I want to minimise the main fs write activity and be able to roll back to a known good state if the RW branch corrupts.
Anyway enough waffle. Some of you have played with the aufs overlay instructions I have contributed to here using ext2/3/4.
If there is enough interest I will release an F2FS image.
When I next update my kernel/initrd.cpio in the main aufs thread that will be good enough to support your own rolled F2FS card, but getting to that point (an F2FS installation) is a non-trivial exercise.
Anyway, let me know you are interested.