The 2% rule seems to be intended to protect against long term expenses (carpet, painting, roof, etc) but if the cost of the home is so much larger than the upkeep expenses it should instead get back to a cost per square foot to maintain-- Example 2000sq ft * $3/yr = $6k/yr for maintenance seems much more reasonable then needing to go achieve the $18k/month route to suggest cashflow.

The most important thing to note from this post is the fact that some the information you are using to make your decision is protected under fair housing laws.

As a property manager, to protect my client, we execute a lease and take the deposit before the house is removed from the market.

My personal residence is a 1500 sq foot 1950's home and I recently had the original fuse box switched to breakers.  

The 1st thing I did was get a lawyer to create a lease that incorporated all of my policies (which he modified so they would be legal and enforceable) and set up a LLC and an umbrella policy to protect our assets.

This is a strategy a lot of people use as they get older, when rate of return is not quite as important anymore as protection of principal.

At 5 units (and I'll assume growing) I'd probably consider switching all of your properties to a program like the one you mentioned ,and there are several others just like it. 

Form your corporation to help protect you personally.  

@Antoine Baisy, consider also Protect America which have some of the lowest monthly costs.   

I also agree about making this a legal entity for protection for the both of you/