Well, from the discussion over at DAZ...

The old Milhorse stuff doesn't work with the new horse.  It could have.  They could have made switchable UVs and autofit work for the horse as they did for Genny.  But they didn't. 

The horse is only for DS 4.5 and Poser 9/2012 with DSON.  People who use older versions of DS or Poser are out of luck. 

The llamas are apparently a morph (or whatever they call it in DS/Genesis) of the horse, so you need the horse if you want the llamas. 

Interesting.  The first step toward a Genesis quadruped? 

Still don't care for the llamas.  They look too horse-like.  They're more closely related to camels than horses.  If I were going to make a llama, I'd start from a camel base, not a horse.