In my opinion, the B9TLs are ideal for the TEN.
Those who think they are over-specified should consider that this makes them more durable and ensures that they will last longer than B5s, and the current vehicles are far from worn out.
I cannot imagine a better model of bus from any of the available current or new stock to fill this arduous role, so suggestions to cascade vehicles from other routes don't appeal (unless they are B9TLs of course).
It also helps a depot if they have identical vehicles for a route rather than a mixed fleet.
Leave the TEN alone (though maybe some additional correctly-liveried B9TLs would make the fleet complete).
