A PA-system should reproduce even the most complex musical signals with depth and definition. This quality should be the maintained up to the highest achievable sound level.
A PA-system should have an excellent SPL/volume ratio, as logistic and storage costs are important factors for most professional users. Don't look for a bigger van; look for a more compact and powerful PA!
A PA-system should be easy to use. This means quick and easy setup. It should be easy to fly, with a minimum of additional hardware, and in the bigger setups, very good acoustic coupling should be obtained for improved long throw characteristics. For the more common no-nonsense applications however, the PA should be easy to stack.
The system should have a well defined and uniform directivity, to ensure good coverage and feedback immunity. Easy wiring should provide quick hookup without any risc of faulty connections.
The integrated amplifiers should be processor controlled for maximum performance and absolute safety for all drivers. Also, amps and speakers should be very energy-efficient, to offer maximum SPL using a common mains power rail.