Some say pay off your mortgage and others say mortgage the hell out of your properties. Let's find out who is right and smack those who are wrong. This calculator will compare your net worth if you mortgaged your investment properties (not your primary residence) vs. paying cash.
Warning: Reality doesn't prevent you from making stupid mistakes so neither will this calculator. If you get weird results then it's most likely you and not the developer cause he is awesome. Use numbers that closely resemble your local market.