Another consideration would be who will carry/manage his health insurance. Insurance policies and rules are managed by each state, unless you are a Federal or Military retiree who has chosen to carry your national coverage (like BCBS Fed) into retirement.

You say "but I am on Medicare..." Yes, but the supplements and/or Advantage plans vary widely by state as well. You need to get a copy of the policy you would have in your new location and read all of the fine print. In the case of opiates and other medications, you need to read everything about their drug coverage and who is their Pharmacy Benefits Manager (PMB.)

I know people who had to go through "step" therapy - trying each drug from A to X on the PMB list when they changed coverage - even if they had a long history & good records to show they had already been through it.

Crazy insurance rules are why several of my Winter Texan neighbors maintain their residency in other states after retirement. It is also why I continue to pay a higher premium for my BCBS Fed plus Medicare B. Watching friends struggle with stupid insurance rules and high copays, forgoing necessary meds, and being miserable has taught me where to economize.
Sue