Baseboard heating in the summer time not so much.

What are the loads in the house: electric baseboard heat; heat pumps; AC units; laundry; other motor loads.I am failing to see why you would need a 400 amp service without a proper load calculation.There is no code restricting the number of sub panels, they only have to have the correct install and protection.If I were in your shoes, I would connect with a licensed and insured electrician and ask for electrical audit. 

We'd be passing through all utility costs to our tenants, so heating/cooling efficiency in that standpoint isn't a concern. 

If you're any more than 0% through the useful life of any of the major systems (heating, roof, etc) you may need to adjust that number accordingly.Same for Vacancy and Repairs.

Back in tech, I majored in Plumbing and Heating and while I excelled at it, my trade just didn't pull me in for a lifetime career.

Does it have central heat and air?  

When I look at an investment rental property I want to make sure it's in a good area so I use crime heat maps and look at the attractions nearby.

It has a large garage I use for storage, but still keep the house heated. 

Apparently, the coil had been replaced in 3 of them. 

Also, snow removal, if you live in a climate with snow and ice.Landlord Responsibilities: Landlord will at all times during the tenancy keep the premises fit for human habitation, and shall in particular:a.Cultivate, care for and mow surrounding grass, lawn, flowers, and shrubberyb.Maintain the premises to substantially comply with any applicable code, statue, ordinance, or regulation governing the premisec.Maintain the roof, floors, walls, chimneys, fireplaces, foundations, and all other structural components in reasonable good repair as to be usable and capable of resisting normal loadsd.Keep any shared or common areas reasonable clean, sanitary, and safe from defects increasing the hazards of fire or accidente.Provide a reasonable program for the control of infestation by insects, rodents, and other pests at move in f.Except where the condition is attributable to normal wear and tear, make repairs and arrangements necessary to put and keep the premises in as good condition as at move ing.Provide reasonably adequate locks and provide keys to the tenanth.Maintain all electrical, plumbing (main lines), heating, and other facilities and appliances supplied by Landlord in reasonably good working orderi.Maintain the unit in reasonably weather tight conditionj.Provide facilities adequate to supply heat and water and hot water as reasonably required by the tenant