To test the demand, I will market one of my 4 units, the next time one is vacant.  

I finished the course and passed the state test within a month.

Then add a clause in your lease to include the instructions on how to test the units and to test them in spring and fall.  

Over the course of the next 20 to 30 years we will build up our portfolio until we reach the point of exchanging into more passive triple net lease class A properties requiring less intensive management. 

You might consider test marketing your area as well as speaking to realtors in your area that specialise in the rental market and determine the occupancy rate as well as the monthly rents. 

If it doesn't pass the stress test, wait for the next one.  

In every test we've done, highly personalized, "real" sites outperform and out-convert more "professional" approaches. :-)

I've already talked to a few people that have used him that say he did a great job so if you want me to get back with you I can after I test him out here in Columbus with a duplex that I own but that fixed rate thing really bothers me too.

Hot markets are for amateurs who think they can make money by buying where the competition is most intense and the prices are highest.  

Does not pass the logic test as FNMA has duplexes and foreplexes as well on Homepath.