Not sure it would be personally. Last thing you want is teething problems to grind the whole line to a stop on the busiest day of the year. Not that the existing stock likely won't do that anyway.
Precisely this, though it's worth noting that in the case of in-service faults, the existing stock tends to either be simple to get going again, or totally dead and cause major issues.
The new fleet is likely going to be a lot trickier to get going again, especially at first whilst maintenance staff fully get to grips with them and work out their quirks.
Off peak during the week is surely the best time where they can cause the least disruption?
The plan was always to have them as 'additional' services at first, remaining solely on Metro's infrastructure keeping everything that little bit easier to control.
It’s entirely conceivable that from Stadler’s perspective it could be ready for service, in the sense that testing may be done and it’s now just waiting for Nexus to train enough drivers. Doesn’t mean that Nexus will have dragged their backsides into gear in time.
Nexus will have timelines with Stadler and if a unit is so close to being ready (a matter of weeks, or less than a week now according to some) then Nexus will be well aware of that. A FOI request to Nexus would ascertain that information.
Especially as some of the test runs have carried uniformed CSAs in the passenger saloon, difficult to see how they can be considered part of the test team so they’d surely be in effect non-revenue passengers.
They are staff employed by Nexus and will have been briefed.
They were trained in Switzerland on the new fleet. They would have to have been signed off on route knowledge as they can't have been chaperoned all this time.
Testing, and running in passenger service are totally different situations, and drivers will *all* require training on driving in passenger service and assessed and then signed off. Those on the testing team won't necessarily need the full training course, but will still require a not insignificant chunk of that training even if they do already know most of it. It's entirely possible some of the test train drivers will actually be the last to drive in full passenger service.
As
@Volvictof has also said, route knowledge and traction knowledge are also not one and the same. The drivers carrying out testing already sign the full network, they sign the units in a testing capacity after carrying out training at Stadler, but they do not sign the units for passenger service.