There are simply too many unknown variables about a property to refine your numbers to 100% accuracy but the more you know about a property, the better your "Guesses" are going to be.As you noted, the down payment requirements on even Small Commercial buildings (< 1MM) are still hefty.

You have to be really careful looking in areas you aren't familiar in because there are SO many variables that go into what makes a property successful.

If I can ask you a few questions about it, I wanted to know what kind of terms they offer, ie: fixed or variable, LTV% and how long the HELOC is good for/open for?

The reason for this is that there are too many variables that affect your taxable income, your effective tax rate and your actual tax bill.

In my experience, the first loan will be variable and fluctuate with prime (libor) plus margin.   

I realize there are a lot of variables that make this in some markets not a good rule and in other markets a pretty good rule. 

I think this can go either way based on so many variables.

After assessing these variables if you're more than (XXXX) years of after tax income positive, I'd sell the property instead of renting, The (XXXX) number is different for each investor based on their business plan.

Big variable here.

There are just too many variables to play with and that doesn't make me feel comfortable.