The thing about Deadzone's cover rules is that it starts with the presumption "If you can see your target, it has cover" and you get bonuses in the relatively rarer situations that the target is completely out in the open. But I can't imagine playing Deadzone with hills or other ground based terrain covering up the grid system. There's a pretty big deliberate synergy that all of the associated building wall tiles for the game are 8" x 8" squares, or accessories for those 8x8 squares. What I remember of Developer talk concerning Dust is that it was operating on a similar principle—you can probably see your target and there’s probably stuff in the way. Honestly, I wouldn't fall down in shock if Defiance ends up with rules (either official or fan-written) to be played on a 1" grid. Hexes would be cute and all, but it's easier to approximate more accurate distance with quick rules like "Diagonals are 0.5 extra each, or 2.0 extra for 5" than to deal with being unable to align walls with grid edges.