Higher performance and heavier aircraft would detract from the Reds' show, as well as being more expensive - in my (not very) humble view.
I watched a Eurofighter doing its stuff at Berlin two years ago. With its computer driven flight characteristics it does things that no Hawk can do. Impossibly tight turns limited only by the ability of the pilot to withstand the 'G' forces.
I'm pretty sure that nine Typhoons with their similarly enhanced manoueverablity would improve the Red Arrows performance considerably. It would also help to sell the aircraft abroad. The Reds tipped the scales in favour of the Hawk in quite a few cases and the Typhoon could do with a bit of international promotion...
The Red Arrows more than pay their way and it would be false economy to ignore the sales potential of the team in promoting our defence industry.