The biggest problem I have with this feature, is that it makes war even more expensive, because you can't loot anything and can only damage each other. Destroy infra/money/tech etcetera.
There will be less major wars in CN because the stakes are way to high, people can lose their nation at a way faster rate now. And can't regain anything for being succesfull at warfaring. You can only get 5 tech and 1 miljon, while you can loose a hell lot of infra, nukes militairy cash, tech. You name it.
With the implemention of planes, also a militairy unit which can only destroy things, and can't loot, we have seen less wars, and now we see even less wars. Because they are just too costly, and no one can really win something.
I suggest you let spies being able to loot like 10 tech, and 1 miljon in cash.
Otherwise I think CN will become a game with less warfare, and where everyone goes neutral because oldschool warfare is too expensive.
If I was in charge I would also removed the 5 tech cap for ground attacks, and just keep the 5% only.
NOTE: I have lost 1300 infra during the last war, I am not like "awwww this will hurt my nation", I am just afraid this game will turn in Sim city game instead of a cool wargame.