Toward the end of the due diligence period we received the final piece of critical info to make our decision: a lease agreement for a cell tower on the corner of the property.

These tenants were rented by the owner, I'm just managing the property more than 7 years ago. 

I currently am a part-time real estate investor that will be leaving my sales job at the end of the year to start investing full time in real estate.

A 58 bps boost.Did you pull those numbers “out of the air”?  

That's crazy the 28 unit is the same cost psf as a Duplex.

What´s the question or advice?   

A lot of out of state investors reap the upside potential of the Nashville market (and protect themselves from some of the downside) by investing in the high-growth (yet moderately priced) secondary markets near Nashville (i.e.

After you get some basic information from there, you should use the enemy method to identify how well competitors do in the area. 

The emotional attachment to the idea of paying off my mortgage early still looms large in my brain though.

What is the deal/analysis advice you seek?