Yes, the risks were running two systems. The risk of running two systems in parallel is that, for example, if someone transfers from one government department to another, then you have no ability to transfer their pay file. The longer we ran two systems the more of a problem that would have been.
Also, we didn't have the compensation staff to do it at the time, because all of them were fully employed on the new system, or were getting ready to transfer.
Those are the two most significant risks. Once we had pulled the trigger in January, unless there were a significant catastrophic problem with the software itself, we almost had to go ahead with the second wave.