If we can compare stock market to a ferrarri, we can compare real estate to a train. 

It seems like he usually just says: "I'll give you your principle + 25% when I finally sell the unit."

Personally I ignore the upside of the good case because I’m a conservative investor and much more concerned about preserving principle than maximizing projected returns.

Hell, historically I can get 8% in stock market index funds with less risk (over time) and zero effort.Do the numbers for what you have now, then re-run them pretending you paid off the mortgage.

Turnkey is more like wholesaling. couple of the big Memphis firms do this and more.. but its all for rental stock true rehab for retail is a different animal as we know.. takes a boat load of capital that's for sure.

Then pay the mortgage (principle and interest) from the other 50%.

On the sales side, SFH that is move in ready is moving briskly on the west side the city so the layoffs and the stock market volatility does not seem to have affected sales much.

Basically what I want to find out is a comparison of a real estate investment versus what returns I could get in another investment vehicle (like the stock market). 

I would never say that a SDIRA or investing in stocks, bonds or the like are not worthwhile. 

A person betting on historical averages continuing for the stock market, would arbitrage the two.