All this cost index stuff makes me laugh.
Do the bean counters realise that if a certain aircraft type is always slower than its counterparts on its arrival, and the controllers are forever pulling everybody else back to stay behind this type, it won't be long before that aircraft type is "saving" money flying round in circles watching all the real aeroplanes fly past while he waits for a slot.
If you can't play with the big boys, controllers quickly get impatient and throw you out of the sandpit, and you'll sit on the sidelines with all the sad Dash-8's and BA146's.