I think that although the Streetlites can rattle and probably won't last as long as a heavyweight single decker but still a decent anough time for what they are (maybe 12 years), the purchase and running cost of them are a no brainer and if looked after, they should have no performance issues.
I will still say that a Red Arrows upgrade with 7x going on the Pronto, 5x going corporate and 2x going on the Angel (and GKN modified) would've been a far better option rather than just buying new Streetdecks for the Pronto. It would've allowed the X1 to become GNE's flagship double deck service second to the Angel (including power sockets which are lacking on the current B9s on there and eLeather) whilst Riverside / Percy Main would've benifited from more better quality spare vehicles (also meaning 6084 could become a more premanent fixture on the TEN due to 6049 taking over the role as the tachograph spare B9). Chester would've also benefited from 2x extra modern Geminis for the Angel and several services and parts of the network would've benefited from the freed B7 Geminis including displacing the 2x non DDA compliant Lolynes on the DFDS work.
RE: Go North East: 2015/16 Financial Year Order Predictions