Most courses I've been through would suggest that you toss the wallet/money clip at the BG where it will be difficult to catch. While the BG is going for the cash, you'll have ample time to make your escape. Drawing down on a guy who already has a gun on you is a very tricky situation and will usually end up in YOU getting shot if you try and draw down on the BG. Money, the money clip, ID, wallet, etc. can be more easily replaced than your life, use of your arms and legs, a kidney, etc. Hopefully we're all diligent out there an have a good sense of "situational awareness", and we see the situation before it gets to the point where we're actually at "gun point".
I'll do my best to get away and call the local authorities, but once the BG starts shooting at me, I'm taking cover and all bets are off. I'm shooting back, and he's going down!