If this was a webapp I'd be willing to pay. I hadn't heard of Sorted before but I do this same technique of assigning a time estimate to every todo item and putting it on my calendar as an appointment. I have a side benefit of these task appointments blocking my calendar so other things can't get scheduled at the same time.
Probably the two biggest peace-of-mind boosts in my life have been this, and blocking of large chunks of time for deep/focused work.