As I was typing up the last post, Amazon saw fit to deliver this!

M9000 derailleur by Richard Mozzarella, on Flickr

Look at the size of this thing! It's the new Shimano XTR9000 SGS (RD-M9000-SGS)
It has a 45 tooth capacity and it's huge!

For the rest of the drive train: I've decided I'm going to mate it with the Jtek Shiftmate #8 (that also arrived from SJS today), and an 11-40 tooth XT M-8000 11 speed cassette. Yesterday a Deore 28-40 chainring set arrived and I R&R'd the large chaing ring in favor of a 44 tooth ring from LX-T671 triple crankset.

I'll be at the 45 tooth capacity of this bad boy and have a range of 19.1 to 109 gear inches with 700X35 tires.
Seems good for touring, yeah?