Quoting Endiel1, reply 5
If i recall correctly, you can't upgrade it to town/fortress/conclave, so I have to doubt it's use. a 7/7/7 is an unbelievable tile, but losing all the fortress upgrades on your troops is pretty noticeable. -6 defense, -2 attack, -25 accuracy, -enmity/bloodthirsty, -2 initiative/-charge/-1hp per lvl......
What troops do you lose? You get more troops, no they won't be your perfect troops from that end game epic fortress, but with 4 essences super early in the game, they are still pretty good. (4 attack + 4 initiative + 4hp + 4 defense for instance) Thats pretty good in my opinion, and your fortress can be 3 essences max (4 with scrying pool, but then you have got a 5 essence one) Oh, and mage troops do not benefit from enmity/bloodthirsty etc. so building mages from that city is almost as good anyways. (the only thing lacking is accuracy)
I never said you lose troops.... looks like you misread my post, although fortresses cut production time in half with upgrades, so a 3/3/3 fortress would train troops about the same speed as the 7/7/4, and faster if it has 4 or more.
Now, say you use fire/ini/hp enhancements on a 3/3/3 fortress with strike garrison upgrade, and fire/ini/hp/armor enhancements on the 7/7/4. The fortress troops would get +25 accuracy, +2 p attack, +1 initiative, +1 def, and give enmity/BT over the unique trained troops, whereas The unique trained would only give +1 fire attack, and +1 hp edge in return. Or take the infirmary option and the fortress troops get -1 ini and +1 hp per level(+0 for level 1).
So they build about the same speed(at the least, fortress builds faster if it has 4+ mat), and the fortress troops are better. I don't see much use the the unique city after early game. =/