Until we get true sync added, I would suggest using the WebDAV option, which tends to be easy and fast. We actually have our own free server you can use (the OmniSync Server, which you may already be using for OmniFocus), and it will function as a WebDAV server to import/export files between the desktop and iPad apps.
Here is the link to sign up, if you are interested and don't already have an account:
<http://www.omnigroup.com/sync/>
All it takes to get set up is adding your email address, then following the instructions that will be sent to you via email. Once you have an account, simply open OmniOutliner on the iPad, tap the Import icon, choose Copy from WebDAV, and enter your info. The server location would be
https://sync.omnigroup.com/YOURUSERNAME/ (make sure to add the last backslash when entering this address anywhere)
To set up an OmniOutliner - specific folder on your Mac to hold your .oo3 documents, open a Finder window, click on Go/Connect to Server, and enter that same sync server address. You will then be able to click on either File/New Folder or chose the New Folder option from the gear drop-down in the Finder window. Name the new folder whatever you wish, add your .oo3 docs, and the next time you chose the Copy From WebDAV option in OO on the iPad, you will see your new folder full of documents to choose from.
Whew! That seems like a lot of work, but it really is easy to set up once you get your confirmation email from us.
We are also working on dedicated Syncing options, and of course we will be adding the new iCloud support once Apple makes it available. I truly hope this helps ease the frustration in the meantime. The Omni Sync Server should be a great, free, and easy option!
I hope this is helpful info. :)