HOODED
I think that trying to compare the inevitable problems that you get with a new into service (especially one that is radical departure from anything previous both in terms of design and the method of product) with aged aircraft is disingenuous.
There is a long, actually very long list of Jet2 events, which in most case appear to be down to age related wear and tear, old aircraft go tech more its that simple, but that does not make them death traps,far from it, Norwegian had a turn back to ALC recently following a engine fire warning and that was on an NG a 14.5 years old one, the oldest in Norwegians fleet in fact and due to be retired from the fleet this winter.
Jet2's business model is and always has been based on the far lower capital cost of using aged aircraft, a very successful business model, the slighter higher fuel consumption and engineering costs still gives them a cost advantage over other operators and allows them to have the required back up aircraft.