So after looking at the armor kits, I could see them maybe being a sort of pre-cursor tech/mentality that leads to full variations/remodels... but I'm not really sure what all they need. I will give immediate feedback, though.
The Yamatai one (the "light" armor) shouldn't boost armor by 5. I get that Durandium (or whatever, I'm not trying to spell their metal right now) is supposedly really strong/capable, but it seems ridiculous that the Nepleslia model is matched in-terms of armor. If we want to go this route, why not mimic the
Full-Armor Gundam, allowing the Nepleslia armor to have multiple smaller shields that get synced up to move in-tune with defensive commands/software? Yamatai's variant right now doesn't seem like it'd be worse off. A higher price to repair/buy alone wouldn't be a good idea, especially if it's faster and matches the durability of the Nep-upgrade.
So, let's either find a way to armor the Nepleslia Nerium with more defensive properties such as a third/defensive arm or reduce the armor gains of the Yamatai suit and amend it to mobility (such as an adept mobility harness. Both of these would give us room ICly and OOCly to further tilt/design the M3 into variants and new forms, but I'm still not entirely sold on it as is. Yamatai's repairs which basically makes it seem just generally like the better upgrade overall. It might be wise to instead of make this an upgrade, make these a sort of equipment. AKA, rather than modifying the structure and requiring a strip, this armor can be fast/hard-booted off the frame in emergencies. It'd allow us to theoretically change how the armoring works (such as the Yamatai armor providing 5 Hull/Armor, while the Nep suit is 10, but both of them obviously can't protect/cover the entire suit) and make a more cinematic tool. I mean, being able to push a button to throw off a suit of burning plates to save yourself or enhance your mecha's speed? It just seems perfect and further increases the "trick pool" that a mecha needs to truly compete with other craft. A mecha is a situational/strategic asset in comparison to a more default/prominent method, after all =3=b