Have you estimated maintenance accurately?

Some of them I am not too keen on keeping due to age (75 years and counting) and the amount of maintenance they required compared to newer properties.

I've never dealt with rent control, but I believe that has more to do with the rate of rent increases rather than forcing you to do maintenance/repairs (though there are certain repairs for safety, etc that must be done timely). 

Also, fewer systems generally means fewer maintenance issues. 

So much deferred maintenance that there was actually holes in the walls and squirrels and critters were living in the home ala Grey Gardens.

In Cleveland, high turnover, no tenant loyalty, high cost of maintenance.

I've started a renovation and maintenance company that caters to investors, PM's and Landlords.  

Talk about your deferred maintenance though!

people living under the same single fam roof/dwelling don't routinely collect RENT from the rest of their family as  LANDLORD-TENANT relationship(s), even if it is their MOTHER IN LAW =Dthus, while the house may have a grandfathered (or grandparented to be more PC?)

Double the insurance, triple the property tax and double the maintenance.