A spur stop trained horse is trained to move forward, backward, and laterally off of your seat cues as well as your legs. They distinguish cues from your calves, spurs, seat and hands down to a fine art. A slight shift of your weight with slight leg pressure might mean leg yield, but when a light rein lift is added it can change to mean haunch turn. It's just a different way of riding. It's actually quite fun to ride an animal so finely tuned. ...and yes they can do all the normal stuff too. My mare knows when it's time to play around and jump or go on trails.
SavvyHill- on a seperate note, I have a nice finished show mare for sale in Oregon if you're at all interested. I'd also be hapy to answer any further questions about spur training if you have them :]