Is being a small PM for someone else worth it?

[Garen T.]

I own 3 SFR's and manage them on my own. 2 of them are a duplex that is <5 mins from my house. Next to me are 2 more duplexes that are owner-occupied, but the owner wants to move. He is on his 3rd PM in 2 years and about to fire this one.

He is asking if I'd be interested in taking over PM role for the 3, and when he moves out it would be the 4 units. 

Rents on these units are in the $1600 range for the 3br/2.5 bath properties. The units are 2 years old and require little maint. B-C neighborhood.

I look at 4 units at $1600 at 10% rate as $7640/year which is not really worth it to me. However, making $7K for very little "possible" effort seems like decent money. This is NOT something I'd like to do for a career. I'm looking to retire in the next 12 months, but at the same time, having multiple streams of income is not something to dismiss.

What are the pro-con list of the PM world? Is there an existing thread here (I assume there are many) where this has been talked about in great detail. Just having a hard time finding them.

Thanks