That's one of the things I liked about the ductless system as well. You are able to somewhat control the rooms individually though. Mine is setup so the nursery is a few degrees warmer than the rest of the bedrooms. We have the Nest tstat upstairs and downstairs and we also have Nest temperature sensors in the 3 upstairs bedrooms. The nursery is always 2-3* warmer than the rest. I don't think its the temperature that's actually controlled as much as its the amount of air being sent through that duct that is controlled.
This actually all started because we are planning to make the conversion from oil to gas this year as well. I said fuck it I am not going another summer in this house with just two window units "cooling" the house. We decided to do the CAC as well. We're still working on getting either a home equity lone or line of credit. Still haven't decided which way we're gonna go with it. For now, we put the CAC on our Southwest card to get the points and will then pay it off once the loan clears. We will then start the process for the gas conversion.
We did solar two years ago I think. The way our billing is set up is that it basically pays for itself. The tax breaks and rebates paid for just about half of the loan. The rest we pay as part of our electric bill. Prior to solar our bill was something like $150-160 per month. Its now down to around $75. Only $10-20 of that is actually power, if that, the rest is the payment for the system. Once that is paid off in another 6-7 years our bill will drop drastically. Although I am not sure how much the CAC system will alter it. I am sure its more efficient than the two window units we had running all day prior. Next I would like to either get a roof peak vent installed or an exhaust fan to pull the hot air out of the attic.