And are insured properly.

There is no mortgage on the property.   

This deal was the catalyst that got me into the mortgage banking industry.

Let's assume your expenses (mortgage, taxes, insurance, maintenance, vacancy, etc.) comes to a clean $600 and the property rents for $1,000.

Btw, you should really consider getting a mortgage on your primary.

And here is where I actually got properly annoyed. 

The proper answer is "it depends" I don't know anything about your case.I do prefer simple over unnecessary complexity.

Each mortgage we have about 250k left on.

that we’ve learned in our 24 years, managing almost 700 doors across the Metro Detroit area, including almost 100 S8 leases:Class A Properties:Cashflow vs Appreciation: Typically, 3-5 years for positive cashflow, but you get highest relative rent & value appreciation.Vacancy Est: Historically 10%, 5% the more recent norm.Tenant Pool: Majority will have FICO scores of 680+ (roughly 5% probability of default), zero evictions in last 7 years.Class B Properties:Cashflow vs Appreciation: Typically, decent amount of relative rent & value appreciation.Vacancy Est: Historically 10%, 5% should be applied only if proper research done to support.Tenant Pool: Majority will have FICO scores of 620-680 (around 10% probability of default), some blemishes, but should have no evictions in last 5 yearsClass C Properties:Cashflow vs Appreciation: Typically, high cashflow and at the lower end of relative rent & value appreciation.

As far as purchase price - I find older homes you can get a much better price on and rehab and still be slightly under market value - and the rent will support the mortgage and expenses.