Jonathan,Unlike credit cards with "Intro Rates", HELOCs are a standard banking product. 

Cancellation policy is full refund less cancellation fee of $200 and any credit card fee is cancelled greater than 60 days prior to arrival, 1/2 refund of total if cancelled 60-30 days prior to arrival and no refund if cancelled less than 30 days prior to arrival.

Link-https://www.hometap.com/end-debt-stress-estimate?

Understanding Commercial LoansProperties with 5 or more units typically fall under commercial real estate loans, which have different requirements compared to residential loans.Requirements for a Commercial LoanCreditworthiness: Both your personal and business credit scores will be considered.Down Payment: Typically, 20-30% down payment is required.Debt Service Coverage Ratio (DSCR): Lenders will assess the property's income relative to the debt payments.

Maybe you mean debt to income?  

I know debt can help you scale faster.

If I sold, I could be debt-free and have extra money each month to invest elsewhere.

(I can say that as someone from massachusetts)But people need to be careful as a CFD is consumer debt and if the borrower contests - all that interest they owe you could be wiped out as if you are not sending statements, I believe the law is then interest could be wiped out and considered invalid.

I also do a Christmas card with some cash at the end of the year. 

We bought at 375k, are currently renovating the basement, and have income of $4725 (before utilities, insurance, and debt service) right now.