This is looking great! Well done.
I second the call for customisable contexts: I am very used to working with @mac, @out and about, @web, @offline etc etc
Making GTD work for oneself I think depends on the ability to have fine-granied control over what contexts your work fits into.
I don't think any gtd solution can shoehorn its users into predefined contexts.
Anyway, I'm along for the ride with the GTD bundle - keep up the good work!