Some of them are, and that's why I avoid webapps when I have a decent native alternatives. I often spend more than 50% of my day without Internet connection. Also, I think that small web companies that disappear after a year or two are not that uncommon.

I've been using a completely paper-based GTD system for a year or so, mostly because I haven't known any really convenient native app for task management. I switched to Org Mode later, but I don't think there was any paper fault in this - it's just that my GTD schemes always collapse after 6 to 12 months and I have to start from scratch. So then I sometimes switch tools.

One disadvantage of paper-based scheme (at least the one I've used) that I know is that it can get noisy when you have lots of tasks finished. It's harder to find an active TODO item between 20 or so crossed out DONEs on a page.

Paper is dependant on:

  - Having paper near your computer.
  - Having a pen that works,
  - or a pencil ... 
  - of which the point doesn't break off.
  - etc.

I use taskwarrior. It's CL and kicks ass. http://taskwarrior.org

You can make yourself a HipsterPDA. Or just have a plain notepad. Having that with yourself is also beneficial for capturing ideas. The only thing that beats paper here, for me, is a one-or-two-clicks voice note recorder in your phone.

Or if you go everywhere with a backpack, you can carry a thin paper binder with your task list with you. I've once used to do both binder and HipsterPDA at the same time.

//EDIT

> I use taskwarrior. It's CL and kicks ass. http://taskwarrior.org

I thought by 'CL' you mean 'Common Lisp' and went straight to downloading the application source. It's not Lisp, it's 'Command Line' :(. Anyway, the app looks really nice.

Command Line = CLI, Common Lisp = CL. I was wondering why being written in Common Lisp made it good.

For me it was more a matter of personal curiosity, since you don't really see much Lisp applications around.