The idea that they are bad is nonsense, aside from the upfront cost of +1 corruption. Do they reinforce slow? Yes, but they also have -50% maintenance along with their -50% reinforcement rate. This means that you can just flat out buy 2x as many banners for every regiment you want to replace, which negates every possible downside. Manchu isn't exactly rich enough to fill their force limit to begin with and everything else is just a pure bonus. The majority of battles you fight are going to have recovery time in between, including all rebels which basically become meaningless rather than significant manpower/ducat drains.
Not good in the mid/late game? I mean, does it even matter? When you have hundreds or thousands of regiments who cares about 30 banners? Arguing about whether they are good or not is meaningless when you can't have enough to matter either way. It's not like streltsy where you can just pretend that Russia has +10% infantry fire as an NI because 100% of their infantry are streltsy. Banners are clearly designed and intended as an early game power spike to help Manchu (among a dozen other things designed to help Manchu) and obviously won't scale unless the player wants to commit to genociding china.
Agree with a lot of points, but you can definitely have more than enough banners. I'm not sure what you mean by that. I could afford 60 banners in early-mid game by just doing some cheap cultural conversions with spare diplo points. (Like the ones that take only 22 diplo points). I took religious ideas thinking that I would be able to utilize the -25% cultural conversion bonus and just go ham on converting every province. But that wasn't even necessary, I got way more than enough banners to go with my artillery.
- 1