If anyone has a safer plan, I want to hear it and it will become my new plan.
I'm not meaning to be argumentative but I think your plan is the LEAST safe thing to do.
The BGs don't share your plan. The odds of getting ambushed/attacked are impossibly high. You don't have backup and Mr BG knows it. He also knows that he DOES have back up and he likely trusts that backup or he wouldn't be doing robberies with him.
The absolute last thing you should be doing is trying to cuff the bad guy. No way, no how. If you want to yell for him to get on the ground, fine. I still think it's a bad idea but do what you want.
Assuming he doesn't have a visible weapon, I would tell him to leave. If he leaves, great, if he doesn't, we're at a stalemate. I'm not shooting unless he's threatening. You can't go looking for his buddy unless he's gone or neutralized.
Again, I can't imagine a scenario where I would try to physically detain a bad guy. No way.