Quoting petrasvu, reply 1Now it impacts money gain (guildars) and research.
I have not noticed this, unless you mean that city level impacts research (+1, +2, +4, etc...) and I guess income. But if that's what you mean, then it impacts production as well.
In my opinion, population right now does not play enough of a role, and as a result, the most effective strategy is to have a ton of level 2 cities... Well, if they somehow grow beyond that, it's nice, but not important.
No i mean that behind that city name value is brought bonus from city lvl AND population. I have checked it few times and numbers were higher that city level bonus let alone, so it looks like population bonus is hiden in this numer also, but not shown separately. Of course if you have nerves testing it out i would be grateful, i would like to find out it if its possible, because its important for my strategies.
By the way you need spam outposts, not cities 
It is enough of 4-5 cities but get tons of outposts around them and claim as many clay mines as possible it will rock your production and everything else then to. I usualy dont care if AI is taking crystal mine or metal, but if i see some clay mines around i try to get them at any cost even starting a war.
