I have been there a couple of times, both without horses or quads. On the second trip some of my party of hunters brought 2 quads, and we used them to get one cow elk out, but the other two cow elk and two bucks we got we didn't need them. Once you figure out where you want to begin hunting you probably will have a better idea on whether you want the horses or not. There are plenty of steep, brushy, thick, etc, areas that don't have roads where a big muley buck would find peace and quiet.
Last fall my brother-in-law was hunting deer there during the third season and it was warm and dry every day he was there, with little sign of rut activity. The year before, 2005, it was getting warmer as the third season progressed after a dump of snow during the second season, which made it easy to get around but deer somewhat hard to find, but the buck i got was rutting pretty good. I found him on BLM ground near Nucla. Good luck.
