Cash out refi vs HELOC

[Matthew Dawes]

Hello BP People. 

I felt like falls in the BRRRR category because that's what I've done with my primary up to this point. Here's my situation. Curious what people's thoughts are.

I was about to apply for a HELOC on my home to buy my next investment property. $250k, 3 yr 1.75%. I would have to pay $3k for an appraisal.

Then I realized a cashout refi might better. My home value is between $1.3m - $1.5m. I owe $650k. My math puts me at pulling $390k out through the cash out refi, with a new higher mortgage payment of about $1650 (to me though this is negligible relative to the equity I can put to better use on a value add investment property).

Is there something I'm missing? Why wouldn't this be a better option? What assumptions am I making that have to be correct for this to work?

Thank you all!!!