I'm a DIY, not professional, so these are from my experience only. Can not comment on the center joint down the length of the house. I have used laminate in house and at cottage.
The house experience showed that you can not get laminate wet - at least not water sitting on a joint for a few hours. We had a spill we did not notice. The joint did swell and distort. Much like a laminate countertop when water gets in the joint and affects the particle board.
At the cottage I have a ceramic tile pattern ( Shaw laminate) in the kitchen and entrance. I put down a plywood underlay over the sub floor before laying the laminate. It has worked very well.
I would recommend an underlay.