What a well-written synopsis. For every passenger that wants hand-delivered trays, you're inconveniencing four or more other passengers in having to do this without a cart. Furthermore, I'd venture that a majority of the people in the focus group who said that they would prefer you not use the cart would be the ones to disrupt the flow by wanting their tray taken before you'd finished bringing the others, be the ones to complain if you took someone else's tray before bringing theirs, want more wine now even though others have not been served their food as yet.

I want a hand-delivered tray, and then I want rapid service for bread, wine refills and to have my tray taken away when I want it taken away. To hell with whether others have gotten their food yet. Oh yeah, and I want a pony.

Cheers.