While awaiting the result, as you mention warranty, obviously the aim of my question is to ensure a long life for the product, and not to void the warranty in doing so. If your Quality Assurance does apply a conformal coating or equivalent to the pcb's, then clearly no point in applying more, although there is then the exposed metal of the mPCIe cards (7260 & SSD), which as observed on laptops in the tropics, internal but exposed hdd connectors have corroded and caused failure. When I worked in design, such failures were reduced using the methods described.
Regarding my inquiry on the country specific SKUs, I was paraphrasing advice I read on the Intel website back around September time, but when searching just now could not find it, but thank you for your advice anyway. So as the cordless SKU is not a preproduction part, I guess I can assume it has no other disadvantages.