The trading posts are a lot more balanced than the cottage economy in my opinion. As it is now, I can't automatically support an enormous army during the modern era. In IV that was easily done, and gold still kept pouring in allowing you to just buy airports in newly conquered cities and dump new units.
I've never seen the AI deal well with a stack of doom. The only thing it does to counter it is put more units into the city you're approaching. It doesn't throw a lot of artillery at them. It doesn't properly protect the few units it decides to throw at it.
If it's too easy, just raise the difficulty. If you're breezing through on Deity, I don't know what you're doing.
I've never seen the AI deal well with a stack of doom. The only thing it does to counter it is put more units into the city you're approaching. It doesn't throw a lot of artillery at them. It doesn't properly protect the few units it decides to throw at it.
If it's too easy, just raise the difficulty. If you're breezing through on Deity, I don't know what you're doing.