In your shoes OP, I like the vending machines, but I'd keep my mind open.

It's much cooler and comfortable during the summer months than where I live in the northeast.

Your property manager's comfort zone apparently doesn't extend to the larger project you'd like them to take on.

As a first-time landlord, I'd feel comfortable renting this out knowing that it will not need heavy repairs and know the area wellWhy renting will not make sense:1.

Given the numbers and assuming you can comfortably manage the property or hire a property manager, I would lean towards keeping the duplex.

In this case, we're still within what I feel is a comfortable range."

What I can say is that the headlines about the difficult tenants and rent restrictions cause issues or a small fraction of property owners - but you'll never hear about the 99% of cases where tenants are paying on time and respect their landlords' properties. if I'm in your shoes, in terms of recommended criteria, I would opt for looking for strongly appreciating areas and not just monthly cashflow.

A shoe store may want a vanilla box, with minimal TI.  

At the end, it's whatever you feel comfortable with. 

Here’s how you can calculate the income requirement:Monthly Rent: $1,680Income Requirement Calculation:Multiply the monthly rent by 3 to find the minimum monthly income required:1,680×3=5,040Therefore, a tenant should ideally have a monthly income of at least $5,040 to comfortably afford a rent of $1,680 per month in the DFW area.