You always invest for appreciation not solely, you always invest understanding it's a physical asset and requires different risk measures.

What measures have you taken to ensure some safety and deter local nuisance?

Common utilities paid by the landlord will be similar if not the same; standard services (extermination, changing filters, snow removal, fire safety inspections etc.) will cost the same.Expenses will vary depending on the market.

I know they have have a stellar track record & hVe never missed a payment, but still I need to understand the safety of the investment in a worst case scanrio?

For that extra psychological safety of handling a that multi-M upscale luxury property transaction maybe worth it, but that's not your market. 

However, if you decide to install HVAC, it should be based on the comfort and safety of your tenants.

It simply is a metric to measure that your odds of getting a return are better.

I really can't say what my average return was because over the decades I didn't keep track, it's not a relevant measurement.

maybe the answer is some sort of Hunters safety course we all took as kids before we got our first guns.. you have a investor safety program that is not a guru LOL..

Chicago's Residential Landlord and Tenant Ordinance (RLTO) and building codes require that all rental units meet zoning, health, and safety standards.