I have a question about how we are defining the 50% rule. 

For most people I talk to in normal, non-forum life, "mortgage" refers to PITI.

When the 50% rule is defined as (gross - mortgage) x 0.50 = expenses, are you considering that variable of "mortgage" to be solely the principal, or the more colloquial "mortgage" of PITI?

@Nathan Grubb 50% rule uses all expenses except principal and interest. If you paid cash for the property you would still have to pay taxes and insurance and that would be taken out of the cash flow.