Cities SHOULD have much more gold than a rural region.
I agree, but they already do. Even without the change the richest rural on Dwilight was Zhonguyan with 447 gold, and the poorest city was Chateau Saffalore with double the gold even though it has 30% less population.
However, looking at the stats to prove my point, I realized it doesn't. With the new change, the richest rural will be Shomrak with 724 gold, richer than the poorest city being Gaston with only 573 gold. I was looking at the extremes, but in the middle it actually mixes things up.
I have to think about it a little more. It may be that the move to powerful City Lords will only be true for the realms with very large cities. That wouldn't be a bad thing, this creates diversity in realms. I was afraid it was a blanket move.
A rural region lord shouldn't be making the same amount of gold after food sales as a city region lord after food purchases. (Which was very common before this change).
It is only common because it is common for city to have many estates and rural regions to have zero or one knight. I am certain that you cannot find a single example where that is true with the same tax rate and estate distribution.