Yes. Chances are the HELOC and mortgage rates will be close to the same. What you are doing in essence is spreading your money around and buying income properties with 100% financing. Return is infinite.
The theory that paying down a property with a DB in order to have positive cash flow is false economics. Cash in a property does not increase or create cash flow because of the fact that the cash must earn a return separate from the property itself.
A income property that does not produce positive cash flow with 100% financing will never have TRUE positive cash flow. Paying down a mortgage creates false cash flow, smoke and mirrors.
I invest and use my HELOC as my business working account, income in, expenses out. I do not hold any cash or emergency funds as long as I leave room in the HELOC.