I could tell everyone the diamond pattern acts like vortex generators.
The smooth side down will be slightly harder to mount, but for skid plate purposes it would be better to have it smooth rather than textured on the bottom. I know you are joking about the oooh diamond plate thing, but honestly I don't want the typical pickup truck-diamond plate stereotypical look. I'm much more used to getting "what the heck is that" attention, I wouldn't know what to do if I got the "I like you got's you lots of shiny on that pickup" attention.
Yeah current plan is to mount a few integrated supports where I have big spans (such as near the center of the underbelly between the frame) , but I want all the panels to mount with quickly removable bolts for ease of removal for maintenance or repairs.