While I have been a RE Investor for 2 Decades, I've seen this metric quite often.

Tells you how to analyze property, how to make the calculations and what metrics you should aim for.

I'm offloading a number of my properties to eliminate headaches, and I've started focusing on a few different metrics (some less measurable than others):-ROE (return on equity)-ROT (return on my time required to manage the property, renovations, or property managers)-ROH (return on headache - my #1 metric.

This is the only metric I care about. 

If you have I moment, I would greatly appreciate your thoughts on the above property, the things I have missed in my initial run-through, and any additional metrics it would be smart to consider when analyzing deals moving forward. 

I'd suggest an inward/outward approach wherein you define specific metrics for yourself and listen to what others have to say about that. 

I've been looking at City-Data for a few different metrics but had not been looking at renter percentage.

Both extremes are accurate for those individuals making those deals but you certainly don't want to juxtapose those two properties/situations and use a single metric (like cash-on-cash) to decide who is the "smarter" investor or what is the "better" investment.   

I think it is all automated based on some metric they use.

Some cities have a much higher percentage of owners versus renters and this has a big impact on the vacancy and available unit metrics.