I have to throw my 2 cents in here.
I've just waded through 10 pages of people debating whether to include priorities in OmniFocus. To me, this only proves two things: (1) a lot of people use priorities and (2) a lot of other people do not. Trying to force one group of users to conform to another group's workflow is only going to end up alienating a large portion of your market share (who may end up turning to other solutions).
I would suggest that priorities be included for those who use them. But there should also be a Preferences option to turn these off, for those who don't.
There is nothing wrong with adding features that some users find superfluous. In fact, this fits really well with the whole "shrink to fit" concept that OmniFocus is based on.
The other argument for including priorities is that both iCal, OmniPlan, and the Palm OS already have this technology installed. If you include priorities it means you can access a 3rd dimention (if you so choose) for organizing your lists! If you don't include them, all you've done is hamstring the other components of your system.
I would also say the question of whether priorities fit with canonical GTD is largely irrelevant. David Allen may have argued against using priorities, but he also says that we shouldn't be outlining our task lists (something that, apparently, we find really useful anyway).
Implementation:
You need to pick a standard and stick with it. iCal defines priorities as: "Very Important", "Important", "Not Important". Similarly, BlackBerry uses "high", "normal", "low" (as does Mail). Yet, MailTags uses "Urgent", "High", "Normal", "Low", "Very Low". And both OmniPlan and Palm OS defines these as: 1 through 5.
All this means is that every time you sync between non-conforming applications, something is going to get corrupted. And if you now throw floating-point numbers into the mix (Curt's slider suggestion), syncing isn't going to have a chance!
Last edited by Adam Sneller; 2007-10-14 at 10:12 AM..