When you are doing a takedown, it goes pretty much the same every time.  They put their hands up, do that stupid little "I'm gonna act like I'm gonna run but NO JUST KIDDING I'm really not" animation, then get on the ground.  As long as you keep your gun on them, there's no real suspense to the situation.  An awesome mod would be one that gives a (preferably configurable) random chance for the suspect to decide to try to get the drop on you in the middle of this.  Pull a gun if he has one and shoot you, or try to run, or, if you are standing too close, melee you, and then either continue attacking you or make a break for it.

I second this request.  In real life, suspects don't always give up just because you have them at tazer/gun point.  Would be nice if it was random and they could still run, requiring you to taze them again and try taking them down again.  The only problem I see is that if you happen to have a suspect who refuses to give up and you taze them enough times, they will die.  That's the only downside to this that I can see.