This is my method for temporarily fixing the lack of OMF in FCPX. It's only worth checking out if you have Premiere Pro and After Effects lying around, and don't mind buying a little program called foolcut AE.
The hack does work, but as you see some clips are out of sync. It's just the audio that's slightly out on a couple of the clips. Most of the clips lined up perfectly, so you have to use the actual audio from the FCPX render to line up any clips that are slightly out.
I should mention that the sync issues don't happen at all when going from FCPX to AfterEffects via foolcut, the software works perfectly for that. The move from AE to PP is where the sync gets muddled a bit.
Yes it is a ridiculous routine to go through, but it works in the meantime and costs a lot less than Automatic Duck if you already have the other programs.
Here's the link for foolcut, it's an amazing little piece of software that's making FCPX more viable.
Hope it helps!
(trivia: it's the exact same phone used in Vincent Laforet's creativelive.com video vimeo.com/27581591 that I helped shoot in March!)