I've been using now SGS3 for almost 4 months. I was using N900 before that for 3 years. I must say, I do not miss mechanical keyboard anymore. I have become quite fast typing with Swiftkey auto-correction, also (and mainly) in portrait mode/orientation. I did have a small bluetooth keyboard with me on a vacation, but I didn't really need it and prolly won't keep it with me on future trips.

I'd rather use extra weight and thickness to have larger battery, than keyboard. I used to think otherwise just 4 months ago.