I dont think anyone can be sure of how successful it will be, but Lui is clearly not the answer at this time. So imo either choose Moltzen or Miller and give them a shot - they cannot be worse than Lui, and if by some miracle they are, then you can bring Lui back and hopefully he will be better for the run in lower grades.
The problem is that we still have Tuqiri and Lawrence out, and have been running without Ellis for such a long time. Add to that problems with Ryan and Utai during the season so far, not to mention injuries to our forward pack in general... and we have two things to take into account - an unsettled backline, and a major test of our depth.
As I see it, Sheens has four genuine halfback options in the circumstances.
1. Play Moltzen, and find another centre (is this why Timona is getting a run three weeks in a row?) Lui to reserves.
2. Play Miller at halfback and hope he handles it. Lui to reserves.
3. Play Lui and hope that he lifts his game. This is the option he's gone with, and we're in sixth place at the moment. Hardly a failure...
4. Play both Lui and Miller in the halves, with one to start and one coming off the bench. The only reason I can think of for this not happening is Miller could be on some incentive based salary and we are under a lot of cap pressure at the moment - maybe they are holding him off in case we need him later in the year?
The real question for me will be what happens when our backline stars return and our full strength team gets ready to run out. Where will Moltzen play? Where will Lui play? What will the MasterCoach™ do then?