The Edit entitlement also plays a role when dragging & dropping tasks into a new projects or doing any updates via the Multi-Edit feature. Both of these features require the Edit entitlement. Additionally, I've noticed that when an item is in the last stage of the workflow the items cannot be edited using the Edit In Workflow option but rather requires the Edit entitlement.
Aside from being confusing to the average user as to when to use Edit or Edit in Workflow, the Edit feature completely bypasses any special field template that you may want to be in place during the edit process. In other words, someone could use the Edit feature to update an item and avoid having to input required information.
I'd like to see Axosoft take another look at the Edit and Edit in Workflow features and get some feed back from the user community on how these could be implemented better.