I think dropping Explorer validity has probably lost it for me as well. Like others on here, I like to mix and match my bus journeys, so need the flexibility of being able to hop on and off whichever bus takes my fancy. However, if I get the special "X11" ticket, that then limits me to GNE services; yes, I can use the X9 / X10 to come back up from Middlesbrough, but if I go anywhere beyond that I'm stuck until the X11 or I have to fork out for an Arriva ticket as well. And my timings also become very limited if I stay with GNE.
Might there not have been scope for an "Explorer Plus" ticket, same validity as Explorer with the addition of the X11? Maybe scope for a small surcharge on X11 for holders of Explorers?
RE: New service X11