At 550 minerals, an orbital costs a lot. When we consider that they provide 11 supply, we can deduct 137 minerals from the supply depots that we would've needed to build. The cost is also mitigated by MULEs. The extra scans that you get by having an extra orbital or two is a very large advantage.
It seems to me that getting an extra orbital command in the mid to late game is a very good idea. Clearly the orbital is an investment that just takes a little bit of time to payoff. Maybe multiple orbitals is something that will change how Terrans play like multiple hatch changed how Zerg was played in SC1.
What do people think about this idea? I've yet to try it in ladder, so I'm not sure if you can get away with dropping 550 minerals like that.