I saw this in a different perspective......
I built the "nano factories" as quickly as I could. Simple reason is the stepping up cost vs pollution area vs production capacity.
Basic Factory = 500, capacity 3, dirty radius 10 x10
Mass Production Factory = 7000, capacity 4, dirty radius 8 x8
High Tech Factory = 20,000, capacity 5, dirty radius 6 x 6
Nano Factory = 50,000, capacity 5, dirty radius none
I built a second city on a second device thinking I was going to build that city in a more efficient way because of the learning mistakes from my first city. And this is one of the areas that I focused on: where and how Simoleans were being spent and how efficient that process was.
To "step up" your factories means that you take a hit on the cost of demolishing the factory you already purchased. They only give you a 50 percent refund of the money spent. I saw this as a waste of resources so I went from Small Factories to Nano Factories in my second city. In order to do this you have to balance the growth of the city to obtain necessary funds to build these Nano Factories - not impossible. You still need a minimum of 150,000 Sims in order to purchase a Nano Factory but I did it with great success and in the end run its better for your city anyway.
Do the same thing with your Power, Water, Sewage and Waster management. Go right to the more efficient services as soon as you can. When you get to later levels in the game you will be better off. And it will save you money from having to "step up" these necessities along the way.
One other thing about this ideal; those more efficient city services and factories also have; as mentioned, the greater capacity. And that means you stay ahead of your growing population, keeping them happy. Once you are ahead of your growing population you can then concentrate on making money (simoleans) thus paving the way for future growth. Something our real city planners do not do today.
nw8240bp