GTD LoFi HiFi Whitepaper
: "I have come to the conclusion that anyone that can use a PDA for GTD isn’t busy enough. What I’ve found is that in spite of these devices being digital and therefore super extensible, they are completely limited in the freedom of motion that they give the user. You are at the mercy of software updates, developers in the marketplace, and hamstrung by limitations in the devices themselves that make it very difficult to manage multiple projects concurrently."
Oh, that explains why I didn't get my GTD/PDA combo working and instead rely on my tweaked Filofax. And I couldn't have said it better.