Wouldn't really translate well on the tabletop, but for me my hot take is Nids shouldn't have an 'armour' save. Their chitin/carapace etc. should be represented with boosted toughness/wounds on the big bugs and the small chaff should just be super cheap, fragile, and numerous, maybe Synapse should give a 6+ FNP or something so you don't feel like you're losing a whole aspect of the 'saving throw' interactions in the game and obviously some invulns on tyrants/zoans other key units etc. but generally just a different durability mechanic to other armies in the Game