It’s true that there is no perfect system out there yet. There are always things you need to tweak either to suit the methodology or your personal needs. There are a few paid systems out there that allow for better context management. I’ve been looking at them recently, but their biggest drawback is that they cost money. They aren’t perfect either. Some have horrendous interfaces, and some trade functionality in favour of prettiness. There are two in particular I am curious about, though, that may serve your needs as they develop. One is the Get it Done app, and the other is Nirvana. I’d recommend you take a look at both of them.
And I also use Grocery IQ — it rocks much. :D