Well put it this way, I'd deem these routes in the North East worthy of a heavyweight powerful decker:

Arriva: X93, X10, X11, X14, X15, X18, X20, X21, X22 (54)
GNE: TEN, X1, X9, X10. (38)

In total including GNE's Northern Spares and Arriva's various spares (Sapphire) that's 92 vehicles. I have very rarely seen an Olympian broken on or on the back of a tow truck. Look at the number of times they had to bail out the B7's on the X9/X10. I agree with economical buses for city routes but for long distance and demanding routes, there is no room for economy to sacrafice power. Power and reliability are first and foremost when it comes to long distances. Economy is a bonus.