Killing it, those are large and in charge.
Ttystikk, I couldn't agree more with you on the benefits of a flip flop. Not only do you get 2 separate rooms harvesting, you have less equipment and cooling requirements like you said (minus the additional cooling for the water since your doubling your system).
Example using our room and 5k watt room:
A/C Cooling... While were running a total of 10kW of lighting, only 5kW is on at one time. So our A/C only see's 5kW worth of heat throughout the 24hour period at any one time instead of 10kW worth of heat for 12 hours.
Lighting equipment... 1 ballast can run 2 bulbs, so 5 ballasts for 10 lights ('Nuff said, lol).
Electrical load... Instead of having 10kW worth of lighting clicking on and running for 12 hours and then clicking off (power spikes, large load). You have 5kW burning 24 hours a day with the DPDT relays switching from 1 rooms lights to the others (eliminates 12on/12off power spikes, constant load).
CO2... Interconnect the rooms with fans exchanging air back and forth from room to room and keep the CO2 constant and temperatures constant in both room. Lights out the plants aren't using co2 but as soon as lights on you don't have to wait for the co2 to fill the room, it's good to go. No need for 2 co2 systems.
Many other benefits I can think of but don't have the time to finish yet. lol
Ttystikk, flip-flop for the win! I'll take photos when I get to building mine if you wanna try a DIY flip/flop. Not sure on your experience so throwing it out there, if you have then shoot me pics. lol
If you go mini-split, you can get 'multi-zone' units that could cover both rooms (or even more!) with only one exterior unit. They just have one wall-hung fan assembly for each zone. Pretty slick ;)