I was specifically thinking about a cash centre robbery. Armed robbers get inordinately long prison tariffs, I would have to be a decent risk reward ratio and I think this is the best. Mostly unmarked bills. I think whenever they transport something really valuable they have a lot of extra security. There's also a lot of variables if you hit them in the open. If I go with Ronuds suggestion and cut the lines then once you're inside a cash centre you have time to work. You will also have more time to get away if it goes well.
On that can you get a mobile phone or signal jammer for a small area. Anyone?