Ben would probably have had more chance of winning on his own. He'd have only had a one step start instead of three, but the time saved from not having to buzz in would have more than made up for that I think. The other two were virtual spectators in the final chase.
The way the bloke in the suit reacted in his head to head when he got through was a bit over the top, to say the least. He'd taken the low offer. If you take the low offer, then you should be getting through. It's not that difficult. You've only got to get four questions right, and you're four steps ahead of the Chaser.