Just remember: most negative reviews are written by problematic tenants.

The rent we charge is on the high side for that area but the zip code is diversifying/ growing a lot.  

As your portfolio grows, your DTI comes down, and before long, you won't be able to get a conventional loan. 

Although our portfolio is growing substantially and we've got solid income coming in, I'm not sure that it's quite at the point where it would stand alone on its own and command financing options (without my wife's W-2 income). 

Run the numbers and remember you want the best deal for your buyer as possible.  

Just remember, if you plan to grow your portfolio you'll eventually need to upgrade to something else.

Historically, our rental prices and real estate prices tend to grow at a pretty consistent and steady 2.5-3.5% each year. 

Remember when you have only 2 units there is usually not much margin to handle vacancy or damage.

What can you do for him that would make him want to work with you and help you grow in your business?

The thermostat is located in one of the units, and I just tell them to keep it at a reasonable temp and remember that the other unit runs off it, and don't turn it off when you're out of town.