I agree with sunrisegirl's summary. My experience is that both KIN and MBJ are zoo's, mainly because of an accumulation of passengers than things like understaffed immigration/customs.

Jamaican residents do get questioned, no interrogated when they arrive, and as a result queues can build up quickly depending on where and when the planes have arrived from.

I have not transited KIN before, but if you can avoid the baggage hall (in terms of picking up your bags) then do it. Baggage handling can be interesting!

I don't know what the lounge is like at the airport, but the AA one is tiny, not terribly comfortable, and not very well equipped...