Rates are so low not sure it is worth that. But using them for investments keeps your money working for you and your heloc is like a reverse savings account with a solid rate of return. I have done this probably 10+ times where I will invest heloc funds and then use all cash flow to pay it off as soon as I can and then repeat.

Can be risky depending on how liquid and leveraged you are and if you Have an emergency fund. 2009 they did freeze helocs were you could not draw on them but fortunately always had cash flow to cover and pay them down.