The keyboard I believe has changed slightly in different versions of iOS. Plus with portrait + split keyboard, this seems like it would be kind of a hassle.
I'm also guessing you won't be able to get the correct angle to type well either.
What about other languages? ie. spanish, it has a different layout. And as far as I know, the layout has changed slightly (enough to annoy your users) since I got my iPad (the old one).
I'm also guessing you won't be able to get the correct angle to type well either.