There is so many variables and potentials in selling, net-0 is NOT an "Investors" action or journey. 2nd-Part; Explore the other ways to REI because I got a funny feeling there is a different segment of the industry that would serve a better fit for yourself. 

I know there are many variables that might prevent a true constructive feedback but I was hoping to get some insights and guidance from this platform. 

Other variables will be income coverage, your experience and FICO, the market, and the property type. 

And it all comes down to your network and sales skills (huge variable)  

There are so many variables to "what it costs" that even if I gave you a number, it could be high or low depending on the actual properties.

Shure, there is blips in variable months but economics is a far slower moving machine, a month is a nano-second in economics time-line.

You mention cash flow several times, so I wonder if that's the most important variable for you...?

I don’t see the sense in paying off my own house at presumably low interest rates, and exchanging that for a higher rate, variable interest line…unless I have a really good plan for not losing my house.  

I don’t like those rates at all, not for a variable interest rate.

@Carlos Lopes mortgage paydown and tax savings are usually mentioned as benefits but rarely factored in the equation for three reasons: 1. they're variable from investor to investor. mortgages are always different (5-30yr terms, different interest rates, fixed/variable rate, interest only / fully amortizing, etc.) and everyone's tax situation is different2. they're hard to calculate because they're "paper" gains.