Thal, I like the plundering idea of Spoils of War in general. It only feels like playing Sid Meier's Pirates! capturing one Spanish Treasure Fleet Galleon after the other at moment.
I don't want to argue too much with plausibility but a defeated military unit after combat shouldn't offer basically a free unit/building as reward. Usually after battle, they are only corpses left with pictures of mum or smoking vehicle wrecks, and hardly bars of gold or American Express Gold Cards. An unscathed sword or ammo box shouldn't justify for a whole unit purchase.
Plundering is more a matter of robbing cities. Yeah, there you can overdo it because capturing cities is the point of warfare in the end: resources and power over others. I don't know the capture mechanic, but you could also make the amount of gold/culture reward depending on pop size besides tech-advancement when capturing cities.
We don't have rich merchant units to rob, except the Great Merchant maybe, in the game where huge gold rewards would be thinkable.
The AI is still not the best unit-formation user and often spreads its unit out and places it in bad positions making it easy prey for a Siege+Mounted/Armor combo attack. Also consider the Barbarians which can be easily farmed for gold this way. Okay, you could reduce the Cost of Barbarian units but the AI isn't much better in the end either.
I've got the feeling you try to put too much balance into policies where it's not really needed. I see it this way with policies. Either I want to go to war and get some useful combat bonuses from Honor/Autocracy or I want Gold and take Commerce. Earning Gold while warmongering is fine but it shouldn't be a replacement for a serious economy.
America in real life didn't help winning the world wars by honor or autocracy either but by a strong economy. The Germans were often more experienced and sometimes better equipped, like picking honor/autocracy, but in the end they were overwhelmed by the sheer mass what the Allies lined up by their powerful economy.
The AI and human players have the choice to pick more than one policy-tree at same time depending on desired/flavored playstyle, and you should really be forced to do that. With Spoils of War, it feels like I'm already settled with everything after my first 4 policy picks in Honor tree. The 50% upgrade cost reduction alone is already a very fine gold-saver.
I'd still like keep building, expansion, combat, economy/gold, production, research, etc. more seperated in policies, that's all.
