(19 Feb 2016, 8:54 pm)tyresmoke wrote Yup, Arriva NE decided to Sapphire the X21/X22 as an upgrade to one of the busiest commuter services into Newcastle, as it is investment from outside of their own budget whilst Sapphire is/was a pilot project by Arriva UK and DB itself. MAX was designed later by ANE/Yorkshire together to improve longer distance services, and has been implemented on most inter urban services across the two regions now (still being done in Yorkshire) as a great way of growing usage.
Apologies for the late reply but surely it would make sense now for X21/X22 to go MAX as it qualifies as an express interurban route that's no more frequent, quicker or used than other MAX services out of Newcastle like X10/X11.