Is that factoring in the HOA costs?

There's always the possibility that they can go up a significant amount based on a number of factors that would really compromise cash flow.

I have a 210K interest only HELOC untapped with a $0 balance and a rate @ 3.75 and I'm looking to do a refinance on some of my other properties and wanted to get a sense of how that would factor in to my DTI. 

That's a matter of long term strategy to avoid ever increasing insurance rates due to hurricane risk factors.  

Generally speaking, it limits your personal liability, is easy to manage, and has pass through treatment for taxes.

Based on the BP Calc, I can make $40k with nearly all holding costs factored in if I buy at $330k.The comps on the high side are $600k and up and all have 4-6 bds.

Normal real estate appreciation, the kind agents and homeowners talk about, is dependent on a lot of factors.

Factoring in for weather (something we don't have in socal) Is a necessary step in the due diligence Nevertheless, for my long term landlording goals, I do believe that this will work.Thank you.

Another factor is what you are willing/able to manage.

The income the property generates is the key factor if a bank can qualify.