If we're talking about and training unarmed defense against an armed attacker (or two or three), remember: an armed attacker ALWAYS has a SERIOUS advantage! This applies whether the attacker has a knife, gun or impact weapon, and whether the attack is "static" (i.e. threat rather than active attack) or fully dynamic (i.e. attacker is in motion to stab/shoot/whack you).
It's easy to prove this in class. We train in efficient methods of knife, gun and cane use in close quarters. If you really wanted to kill your classmate, would you stab at him slowly, gently or predictably? Would you lock the handgun out in front of you where he could easily deflect it? Would you take long, telegraphed swings with your cane or bat, and keep swinging the same way repeatedly? I would think not. I think your attack would be extremely deceptive, unpredictable, short, fast and aggressive. With your level of skill, would you be able to deal with such an attack from your clone?
A real attacker in your home on in the Walmart parking lot may not have as much training and skill as you have. Then again, he may have greater fighting attributes and far greater experience with real deadly force. You never really know whom you're dealing with (a apparent weakling can get stupid strong and fast if s/he feels threatened). You CANNOT realistically expect him or her to be predictable. No matter how awesome your gun disarm technique, you can't guarantee that your attacker won't move the gun just as you start to move. You can't rely on him to draw back his bat before hitting you, as if he's stepping up to hit a home run. The quick jab with the bat he lands on your kneecap before you were "ready" may just gain him a nice immobile target for his subsequent home run swing.
Yes, some level of cooperation must be present in training in order to allow the student to initially learn the concepts and movements. However, this cooperation should quickly and progressively deteriorate, forcing the student to adapt (developed in contact flow practice) to survive. Assuming students of relatively similar skill and attribute levels, and leaving aside situational/behavioral aspects and tactics such as ruses and use of cover, as the cooperation level drops to near zero, the unarmed student's success rate should also drop to near zero. Unfortunately, that's reality.
Solutions? Be aware. Avoid trouble. Be armed. Go first. Leave as little to chance as possible. And remember, no matter how skilled and prepared you become, in the right circumstances, anyone can kill anyone. Good luck.