Realize this option is extremely volatile especially since we would still need to maintain and upkeep the property. 

If you hold a really, really long time where you can cycle back again to sell when the market is strong it might make sense.For other investors who hold for up to 10 years tops the short term might not work as they have to sell in an in opportune time in a volatile market.

Here's why:The property services its own debt through rentsThe long-term return on capital (or equity) is magnified exponentiallyTraditionally real estate appreciates over timeRents are not volatile and do not fluctuate with the short-term ups and downs of the house price market.  

Definitely worth a read.Ultimately, the article ends with:It's a riskier choice [investing in housing], given the current volatility in home prices, but it may be the best way to build wealth.My opinion?

The tech market is still on fire, albeit with volatility.

In fact, I'd argue that in many markets commercial (at least multi-family commercial) is more overvalued than residential.You are correct that free and clear reduces your volatility (both to the up side and to the down side).

However, rent volatility increases as well.  

They made a nice run up but now feel volatility is coming in the future and want to cash out gains and put into a more stable cash flow environment.How busy does your business, job keep you??

Properties with issues have prices hurt by volatile markets.

I would agree with Thomas S. that just borrowing money and investing it isn't going to get you the money you want to have.In Silicon Valley less desirable homes are more volatile.