They do have good credit but each one should be evaluated on its own merits.

Not saying those things don't have their merits, some do and some don't.

We can debate the merits of the "primary residence" provision, but it is what it is. 

I just have no experience in the commercial real estate side so I am trying to do some market analysis to see if people in the business also think there is some merit to the idea.Where better to ask than on the Bigger Pockets commercial property forum?

From a metric standpoint, many investors (myself included) find them much more appealing and they tend to cashflow considerably more per door than a side by side duplex.All that to say, a each deal should be analyzed individually and a decision made on each of it's merits. 

Without understanding each in a very detailed way, it would be difficult to give you advice that would hold much merit. 

I'm open to various commercial RE segments for diversification and would evaluate each on merit.  

They don't want me to buy a new washer and dryer, just that they get to use their own machines.1) I know from past experience that most tenants test landlords in the beginning of a lease to see who has control in the situation. 2) I'm tempted to go and run a load of laundry through the washer and dryer myself to see if there is any merit to this claim, rather than just letting them do it.

You need to analyze each property on its merits.

I haven't ever had someone sign a 2nd contract after mine was receipted, but this seems like something prudent to do if there is sufficient equity in the deal to merit protecting yourself.