I think Graham's comment is a good summary. For many years I ran a DofE group in N Yorkshire. Now retired I assess in the Cairngorms.
Safety, and particularly with stoves is the main concern. Trangias have a low centre of gravity and are tolerant of slight misuse. The objection to some gas stoves is their high centre of gravity and lower stability. However any DofE expedition group that can convince their supervisor that they understand the safe use of their chosen stove has made a good start.
Personal kit needs to be functional and there will always be wide range of choices made.
I have also played the 'lets see what we can throw out of your rucksac game' and always make clear that there is no virtue in carrying a big load.
At the end of the day the expedition belongs to the young people concerned and a big part of it is planning and that includes all the gear.