I guess I overlooked the keyboard addition. But would you say that a laptop provides a better interface? Or do you like the iPad more than a laptop for writing? I haven't actually used a keyboard with a tablet, so I don't have any personal experience with that.
I find my ipad with a dropbox compatiable editor is sufficient for my writing needs, but my laptop is certainly more efficient. For anything other then sustained reading or using a highly specific app my laptop is definitely faster and easier to use. I just find portability to trump efficiency in a great may suitations. If am at my desk I want my MacBook Pro with it's vastly superior sound card and my Grados. Anywhere else, I'll take my iPad and same earbuds if I don't have any programming to do.
At home I do carry it everywhere. When I go out, I have a 10.1" netbook bag which holds my iPad, keyboard, camera, charging cables, and earbuds. It's easy to carry around everywhere even to resuarants and the local B&N store.
I only use the keyboard when I plan to do a lot of writing. Right now I'm just using the software keyboard.