Hi I think i found a way to work with Omnifocus and Autofocus efficiently. Still testing but seems working. See my blog in French http://gtdway.blogspot.com/

The idea is simple
1. paper works well for actionable tasks
2. Omnifocus is great for projects, dated tasks, non actionable tasks and incoming tasks and GTD IN informations.

And The solution is : Do a daily review !
- Report all actionable tasks from OF to AF
- Repport all dated tasks on OF, unactionables tasks or futures tasks
- Manage your project on OF and use the NOTES (you can have a page)

Advantage : The only things your are working on are on AF so you can easely focus, all your future tasks and non actionable tasks are on OF and you manage everything from your project notes. You dont loose your time reading unactivable task (but only once or twice a day). You eliminate all unusefull task definitivly from AF and OF, so it's clean. You can trust the system because you know what's about your projects & even repport all essential done tasks in OF & you know what's are your actionable tasks without loosing time readings projects or contexts.
difficulties : You must do a daily review to see what is actionable or not