With residential rentals, long term vacancy should not be a factor. 

You email the link, they click it, fill it out, pay the $35 fee, and the results come to me.

I know that the equity is the most important factor, but if the ROI is great, and the purpose of the Sub 2 is a long term buy and hold strategy shouldn't that make the formula more flexible, since the equity would build faster with a higher ROI?  

I suspect I know the area, but I regardless having looked at a bunch of duplexes in Dallas, I cant imagine that you can cash flow with $4,100 in rents and a $659K purchase price, especially when you factor in property taxes, management, capex etc. the Dallas Property taxes are very high since there isn't any state income tax. 

I would increase that percentage with other factors, such as if the hourly painter came from a reliable referral source.In a nutshell, an hourly painter to me sounds inexperienced and better be waaaaay cheaper than everybody else.

I’ll look at the attached link. 

Let me know if you want that link.

Thanks @Eric Teran for the link to your other article, it was very helpful.

Although a private letter ruling does not establish legal precedent for all investors, there are many advisors who believe two years is a conservative holding period, provided no other significant factors contradict the investment intent." 

There is so much on the education link that I am sure you will find it a great resource.