A couple of extra (though perhaps less significant) disadvantages to the city are the time and cost of getting the walls up and the fact that the settler/engineer used to found may have a more effective use. (As for example, bearing the barracks point in mind and subject to terrain, founding on a more potentially productive site in the hinterland of the choke point fort.)I cannot resist recounting a sad setback which I have just suffered in my current game. I had a marvellous choke point which was keeping the Mongols a good comfortable distance off and which guaranted me the opportunity of expanding into this excellent intervening land with plenty of specials and a simply enormous river leading straight towards the Mongol heartland on the other side of the choke point.
They had kindly built a hill fort at the site and had garrisoned the fort with a legion. But when my own legion entrenched itself on the hills next door the Mongols would not tolerate that and attacked. They died of course allowing my legion to move in. I marched a second legion and a dip over and felt smug.
Later they sneak attacked the fort and destroyed one legion with a cat (the sneak attack bonus at work I think, if it is proved to exist). The second legion saw off its attacker but was injured.
I was faced with two units left next to my fort which I could bribe with my dip. The cat (just barely still in one piece as a result of my deceased legion's stout defending) was sat on hills and a newly arrived and uninjured elly sat on flatland.
The dip spoke to each and established their price. They each wanted about 180 to 190 gold and my Republican treasury could cheerfully afford both. But just before I went ahead I said to myself, well an elly is soon going to be a pretty redundant unit (Gunpowder imminent) why spend so much? The cat will go on being useful and has enough fire power, once repaired to hit units venturing onto the hills next to the fort.
So I used the remaining legion to kill the elly (my legion dropping into the red while doing so) and bought in the cat.
HORRORS. Buying in the cat revealed another Mongol legion and another Mongol elly! I surveyed the scene. My dip was now toast, sitting next to the powerful Mongol units and having used up his two movement points moving into the cat's hill square. The cat could retreat into the temporary safety of the hill fort but would be attacked before it had time to repair itself. The legion would not, badly hurt, keep the Mongol units at bay. Pathetically, I sued for peace but no dice. A caravan was in the vicinity but, healthy as [i]that[i/] unit was, it would need to be lucky to see off the elly or legion once attacked even in the hill fort (in the event it very nearly did, but crucially not quite
).
So consider. Had I bought in the elly followed by the cat, I would have had a serviceable legion sat in the fort plus a healthy elly. I would have moved the cat in with time to repair itself. In all likelihood the dip, having used one movement point in bribing the elly would not have moved into the hills when bribing the cat and hence would have stayed safe and able to bribe again or to move back into the fort next turn. So I would have had plenty of resource available to deal with the Mongol units as they came on. The caravan would have continued on its peaceful and potentialy profitable way. My healthy bank balance would have dropped but by less than 400 gold and the hill fort choke point would have been mine to this day. As it is, I lost the caravan, the NONE vet legion, the bribed cat, 180 odd gold, the dip and, crucially, the splendid choke point.
I could not but think that my decision making had failed to star!!
As a final comment I suppose this exposes another small point in the city -v- fort debate. You can use the city screen to get news of enemy unts within the city's area which are not in sight on the main screen. So I wouldn't have made the same blunder.
Conceivably there is another benefit in that if you keep the city at size one you won't have to re-take it if it is lost to frontal assault. If I'm going to try to get that choke point back I face having to attack the hill fort which is, of course, still there.