Let's start with the biggest risk of all: will the Roth concept survive?

It is one of the negatives of people sharing walls or floors in this case.If the third floor tenants are a real noise problem, they could drive out your second floor tenants and even drive out future tenants. 

For you the DMM mere mortal people... you are starting from negative ground!!

Let's use the illustration of driving a car to help you understand the concept.

You'll also probably get negative cash flow if it is a long term rental and you account for all expenses, but you'll make money off appreciation.

I am learning how to analyze deals but almost all of the properties that I analyze have a negative cash flow.

Usually this difference is minimal for most involved in REI (the difference between $500 and $1500 avg) but for for negative cash flow situations or beginners it could matter. 

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

I'm new to this concept and want to charge a fair price for this but also cover my risk. 

It's a great concept but hard to execute.