I always thought, from the position of never having used the system, that the whole point was that the person flying the approach head down was going to go around. This is meant to remove the problems associated with transitioning from IF to visual in marginal conditions, and also to avoid the inadvertent minimum bust caused by the "but I must be able to see the lights now" factor as you continue decending. So approacing DH the monitoring pilot is (relatively) free to look out for the visual reference and if visual at the DH takes over to land. If (s)he is not visual, or if they've just had a heart attack and don't respond then the flying pilot does it just like in the sim and goes around. It sounds remarkably sensible and ought to be straightforward as long as everyone knows what to expect.
Rainboe, I think that in the context of airline ops your comment about "inexperienced and poorly trained pilots" is farcical. They almost certainly have less experience than the captain; at what point do they cease being "inexperienced" - in most airlines' seniority based system people are capable of being captains long before they ever get their command. And again most airlines training systems are pretty thorough - even Ryanair don't skimp on what they do, they just get other people to pay for it! Having said all that, in reality when flying with an inexperienced/ poorly trained fo (as happens quite frequently in the corporate world), by far the best way to operate is to get them to fly the aeroplane, leaving the captain to manage the flight effectively while giving them a great sense of satisfaction!