Looks good to me.
Lots of parents and students claiming that ‘they always pull it out of the bag for the real thing’ but, in general, the cohort I teach ranked pretty much as expected in the mocks (with a couple of exceptions).
They all improve at all schools between mocks and real exams, everyone knows this.
And the grades will be moderated so, at school level, there is a similar distribution to previous years.
Like all systems (including normal GCSEs and A levels) there will be a random element, but I suspect the results judged by teachers who have known students for years will, on average, better represent pupils’ potential than an assessment sat over a few weeks in normal times.
Maybe we will end up with this system all the time as long as we find a way to grade schools fairly, so as to avoid rampant grade inflation.