Downpayment: Should I be using a HELOC or my own CASH

[Timothy Au]

Hoping to get some advice. 

I've been buying my investment properties with 25% down of my own money and recently another investor recommended that I should be using my HELOC for the downpayment to allow me to write off the interest on the downpayment.

Does anyone have any comments or insight on this advice?

I asked my CPA who basically said "yes I can do it" but didn't provide a recommendation if this was beneficial or not for me.
 

I am in the highest income tax bracket if that matters any. 

Thanks in advance.