I've been using OmniOutliner since 2005, and though I like it very much, my main frustration is the lack of filters. As an old Ecco Pro user, I know how deeply filters can extend an outliner's usability. Let me give you a specific example of how filters can work (and please forgive my cross-posting this post on the OO4 forum as well).
Let's say you want to create an outline to collect recipes. (I can't cook worth a damn, so my recipes outline would consist of only two items: Buy take out, or Ask the wife for food.) But let's assume for a moment that I was an experienced cook with tons of recipes I've used or adapted through the years.
So I'd create a Level One item which consists of the name of each dish. Level Two items indented under the name of the dish could include Ingredients, Directions, and whatever else I wanted: notes on who among my frequent dinner guests like or don't like this dish, pictures showing what it's supposed to look like, a link to an online video showing how a master chef prepares it, etc.
Then I'd make four columns:
MEAL: a pop-up list with three choices: Breakfast, Lunch, Dinner.
CALORIES: a number list into which I'd type the number of calories per serving.
TIME: a duration list into which I'd type the total time it takes to prepare this meal.
MAIN INGREDIENT: a text list into which I'd type the name of the main ingredient.
I would then enter hundred of recipes. (Remember, this is fiction. I know only how to burn toast and hit the button on the Nespresso machine.)
The phone rings. It's George and Martha wanting to come over for dinner. I know they're both on diets, and they love pasta. I also know I won't have a lot of time. So the first thing I do is open my enormous Recipes.004 outline, click on the View Menu, and select Filter. A Search Box opens, with choices not unlike those we use when creating a Smart Folder in Finder. Using the little plus sign, we can add search criteria such as Meal = Dinner ... Calories = Under 500 ... Prep time = under 45 minutes ... and Main Ingredient = pasta.
When I hit enter, the main outline - which contains thousands of recipes - now shows me 3 recipes whose columns match the search criteria. Three pasta dishes under 500 calories, that take less that 45 minutes to prepare.
Now I open the sidebar, go to Batch Find and enter George and Martha's names to see if I've ever made a note in any of these about them. Sure enough, there's a note that they loathed the Sardine Linguine with Unsweetened Chocolate Sauce, so I'll scratch that. Another of the recipes has a note saying they loved it. But the note is dated yesterday, so that might be a little too soon to foist it on these freeloaders. That leaves one other, and that's what I'll make.
Imagine trying to sort through all this without filters.
If one of the criteria weren't that important, say Prep Time, you could search for the other criteria, and then sort that list by clicking on the Prep Time column and choosing Keep Sorted: Lowest t Highest, and then you'd see that filtered list sorted by shortest prep time to longest. Or by calories. It's hugley customizable.
I used Ecco Pro for years in countless ways because the filters allowed infinite flexibility. Every project, every hobby, every area of interest, pretty much everything I did had an Ecco outline. I was using them far more often than I currently use Omni Outlines, because Ecco's filters allowed me to see my data in different ways, and therefore in more useful ways. All I had to do was to decide how I wanted to look at my data, and in a few seconds, it could be done. It was amazing.
Another quick example: I had a very complicated project at work that involved multiple cities, multiple departments, multiple individuals. If I were speaking with multiple department heads about one aspect of the project, I could filter just for that aspect, and then see the data organized by department. If I were talking to one Department, I could look only at those items assigned to that department and sort it by priority, or by status. If I were on the phone with someone in the Vancouver office, I could sort the data so I saw only those open items that involved Vancouver. Etc. It was remarkably useful, and kept me more organized than I've ever been before or since.
Please note this is not a Task Manager. OmniFocus does that brilliantly (and its Perspectives are a pretty good approximation of Ecco's filters). OmniOutlienr with filters would be for managing ALL the information on a project, not just tasks. Plans, ideas, notes, research, links, etc. Anything and everything related to a project can go into an outline (instead of into a folder as separate documents).
I understand this is not currently part of OO4 because this has not been a frequently-requested feature. But my guess is it's not frequently-requested because so few of us have ever seen this capability in action.
I'm quite sure OO can have this feature without too much difficulty. OmniFocus has Perspectives ... so could OmniOutliner. If you agree, please let OmniGroup know. It would be a tremendous capability for a great, but currently-limited Outliner.
Thanks.