Here's a practical example.
My wife asked me a few minutes ago if there might be anything we should buy today (Amazon Black Friday sales) for our current home remodel project. I opened TB9, used the attachment search for all thoughts with .taskpaper files, clicked the applicable file which opened in Taskpaper, found an item that might apply, right-clicked it and shared it to Apple Reminders which made it available on all my devices. It defaulted to my Today list in Reminders. The downside to this is if I complete it in Reminders, it will still be in theBrain. That sort of thing used to bug me, but seriously, I'm going to see it when I review again, plus if I really needed to clear it off of some list it would also mean I needed to create a follow up task which I also would have captured in Apple Reminders. If I was on the go I probably would have used Siri. If I was still at my desk it would have gone directly to a Taskpaper list. In this case Amazon didn't have what I was looking for, so I marked the item complete in Reminders and left it on the Taskpaper list. Summary: I'm using Apple Reminders to catch items quickly, Taskpaper docs created within theBrain for project management (one per), and Omnifocus for managing my scheduled reviews and more complicated (nested, etc.) lists. I think I'll eventually phase out OmniFocus and use just a calendar. I'm hoping the iOS version of TB9 will create some new conveniences. I'm also anxiously looking forward to the return of the TB9 calendar. It sounds like a great fit.
iMac (Retina 5K, 27-inch, Late 2015) 3.3 GHz Intel Core i5 32 GB 1867 MHz DDR3