And, just like that, I got my answer. Nathan, from Proof, just emailed me, on Christmas Eve, no less.
Apparently the 1 in 8 on the 26" is a new part for them. It sounds like they aren't planning on a 1 in 8 28" anytime soon.
So, I guess I have to decide if I want a 28" 1 in 9 or a 26" 1 in 8.