A cap rate is a specific calculation that tells you at what rate the MARKET is buying an income stream for a specific property in a specific location, at a specific time.A cap rate is generally not used for small residential properties mainly because these owners do not report accurate income and expenses and there is no place where this information would be analyzed and reported.

I am looking to create a second income stream via real estate and not selling people and getting into real estate.

There are a few serious investors and a continuous stream of ever-changing wannabes and newbies.

Social responsibilty of the investmentMy list would include other factors such as level of activety (passive vs active), COC return, ability to mitigate risk, ability to protect principle while keeping growth, and a comfortable margin between income streams and growth.

Account ClosedMake sure you have adequate reserves then with anything is excess of that I would look to adding additional income streams. 

One thing that I don't think has been mentioned in this stream would be to allow pets.

I help and show people who to create streams of income through multi-family investing.

I know of Prop Trend, Prop Stream and freedom soft. and a software pack that is thru Kent Clothier that is a full blown version of comps now.

You are correct that it is a stream of  4 renters vs. one larger lower rent home.

Ultimately, we all need cashflow, but converting a pile of money (such as in a 401k) into a stream of cashflow is extremely easy.