Domino (plus at least 2 sprints), Dice, Chaparral (4x models), Techno, Slysz Bowie, Hungarian, Foundry, and sprint runs in the Military, Manix 2, PM2 (I may be forgetting some here).
There aren't a huge pile of them, but there is a fairly diverse group of knives in the steel. One common theme: they're all either sprints or fairly higher-end models. I think they bought a big batch of XHP from Carpenter when it was newer and more expensive/premium. Now, when it's less expensive, it would probably be used in the models using S30V, and I bet they have a LOT of S30V in stock and/or a really great deal with Crucible for it.
I'd love to see more XHP models; I really like it on my Techno and Chaparral (carrying today!). It would be nice to have it as another option for production knives in that price tier. That'd be pretty easy I think for the Taichung knives (Sages in XHP?) since they're already using Carpenter's BD1, and I've heard they're sending S30V to Japan so maybe XHP too. The trick would be the Golden knives. They currently have two Crucible production lines (S30V, S110V), but they also have Carpenter models in BD1 (UKPK, Manix, Pygmy Warrior if it's still in production), as well as the new Maxamet models (if those are actual production, and not sprint/limited).
I dunno. Would folks want to see the Golden BD1 or S30V models in XHP as well? Would that even be feasible for Spyderco to do ?
Current: Dragonfly 2 ZDP-189, Chaparral 1, Techno 1, Delica 4 HAP-40, Dragonfly 2 HAP-40, Mantra 1, Ladybug Salt Hawkbill, Nirvana CPM, Endura 4 HAP-40, Sage 4, Para Military 2 CPM Cru-Wear, Sage 5, Caly3 HAP40, Sliverax, Lil' Nilakka, Chaparral Raffir Noble, Zulu, Manbug HAP40, Meerkat HAP40, Sage 1/Sage 2/Sage 3 CF, Introvert, Techno 2