Attended a RAeS lecture last night by the Aeralis Chief Engineer.
Design is pretty much frozen, Hamble Aerostructures have done all the airframe CAD work (traditional aluminium airframe, very little composites), systems design is well advanced.
Change from mid to low wing followed wind tunnel work to reduce drag, and increase speed for aggressor role.
Expected that most aircraft will stay in the format they are built in with little role change in use.
Much emphasis on life cost savings if there's a mixed fleet of trainer/aggressor etc.
Options for easy change of engine as new designs mature.
Core aircraft is up to 85% common across versions.
Aiming for 55mins/flying hour maintenance - 92% availabilty.
It appears they just need someone to order it...