This seems reasonable to me, but it still leaves the question of what is the advantage of a TI over a TM?
Assuming that you can move TIs, the three options have the following advantages/disadvantages
Terraforming InstallationA: No maintenance required. Can be moved
D: Requires manpower
TM on a shipA: Flexibility in terms of location. No manpower required
D: Requires maintenance and overhauls, plus the supporting systems on the ship.
TM on a PDCA: Cheapest way to build them. No manpower required. No maintenance required.
D: Can't be moved once built
Steve