Quote Originally Posted by DanielBaird View Post
Anyway the question is: are there iOS mobile apps that actually implement GTD workflow without me having to carefully fiddle about mapping the app's idea of tags and priorities and whatnot into proper GTD concepts?
Things and Omnifocus are close to what you think you want. However, there are always trade-offs. If you have a large number of projects, for example, you may find it tedious to assign each next action to a project. The requirements for a minimal gtd list app are much less that what you list. In this regard, I might point out that "catholic" means widely inclusive, while "canonical" means according to recognized rules.