Stockport and (I believe) other Avanti managed stations. I also notice them being sold at Newcastle last year.
Admittedly these are only at ticket offices, not ticket machines.
I'm surprised. I wonder what happens if you want a cross-London ticket.
On an unrelated note, I would feel more confident taking e-tickets if they were direct emails like National Express or hotel bookings, rather than a PDF attachment that for all we know will not even open.
That one's never bothered me. There are so many ways of viewing a pdf these days. And unless you've bought just before travel you've got a chance to make sure they do display before actually using them.