It depends on your goals and risk tolerance.

I just stumbled upon it online and I’m trying to research it myself. 

If you're considering investing with them, verify every number line by line to avoid costly surprises. 

Owe 40k left with 8 years left on mortgage.

When I asked why I was paying for a service fee during a period where I never turned on service, the customer service person explained that even if I didn't have service turned on, and there was no usage, there is a monthly fee for the line that runs from the street to my house so that when I reconnect, they don't have to rip up the ground and put in a new line.To me this sounded ridiculous and the power and gas companies are not charging any such fees. 

Can you secure financing on a NNN lease? 

In the more suburban areas of the City towards the County line, you may find smaller duplexes or 1930s craftsman/bungalows that are split into 2-3 units in areas where the values are much more affordable, but also not in the City center.

The main thing is making sure your investments produce a return that outweighs the cost of the borrowed money.A full cash-out refinance could work down the line, but with rates where they are, you’d be trading a 6.25% ARM for something likely higher, now that it is not an owner-occupied property, which may not be worth it unless you really need the capital to scale.

If they’re just using the stove like any normal person would, that’s on us as landlords.

I'm still focusing on small multi-families mainly 3-4 units.