Anyone see any drawback to this i am missing?  

There are drawbacks though, you now have a larger payment and less cash flow.

@Carlos H DeOliveira - Even though I have a condo that I am renting, for a buy and hold investor the only drawback is that most condos have a cap on the amount of units that can be rented at any one time.

I'm not trying to discourage you from looking at properties that meet the 1% ratio but just wanted to inform you of some of the drawbacks of only looking at the 1% ratio when evaluating investment properties.        

Do you see any drawbacks to putting all of our cash into our mortgage and relying solely on our HELOC to get started in real estate investing?

Each strategy will have different strengths and drawbacks.

The lower periodic payments are nice but a drawback is that the balance of the loan declines more slowly.

You've got this huge journey ahead of you and you can choose between a number of different character classes (banker, farmer, carpenter etc) each with different starting bonuses and drawbacks.

I am relatively new to investing but can anyone see any drawbacks to this?

The drawbacks for condos in Dallas and Fort Worth from what I've heard is that condos are spaced next to and above/below one another.