About “The busses will be smaller instead of the larger COBUS used and more of them”, is that being done because of substantially lower fuel costs for the smaller transport vehicles or because of some kind of greater ease/lower cost to find eligible drivers for the smaller vans?

One of the last times when I used the airside bus for an evening transit to T5, it got rather tight between the passenger count, the cabin baggage and a couple of valet-tagged strollers.