We're just starting to move over to tablets-with-keyboards for our frequent travellers. The price point is now down to a level where they're a viable alternative to laptops, and they have the option of taking the keyboard or not as required. We're strictly Windows though, not iPad.
Part of the reason to change was a lack of decent small-screen laptops.
Anyone who is mainly in the office and needs something they can take to the conference room, home or occasionally to another site still gets a laptop though.