In the end, I just ended up reverting back to keeping a simple to-do list in a text file.
Just following it for a short time made my work & life a whole, whole lot better.
I've also noticed that most things I put off, or forget to do, are things are I don't actually want to do anyway and no amount of GTD-ing or tasklisting or anything will ever make me do them. They are just cruft that accumulates.
Better to just let them slip off your viewfinder. One thing I have to improve, though, is doing that consciously. Instead of letting things slip through the cracks, I have to start consciously pushing them through the cracks.
To make a counter argument to your "methodology": There are "small" things that don't seem important relative to other things, but as you get more organized, getting those "small" things done can be very satisfying. Also the energy needed to do them may be small when you remember them in the right context.
Like any new habit you can't hope to form it in two weeks, you need so sustain the effort for at least a few months.
(To be honest, I have experimented with various GTD systems along the years, and was not able to sustain it as well for longer than a few months. However, during crunch time, I find it an incredible tool)