I think the main drawback is being on a Prepayment Penalty in a rate decreasing environment.

There is no mention of the loan balance, just the rate and payment (I did the math on $513 / mo - if it's principal and interest only the loan balance would be $92,900 - so I suspect you're quoting a PITI payment). 

Each town has its own benefits and drawbacks, so be sure to research them based on your rental approach.

Personally, I have no issues making the full monthly payments from the start, so it seems unnecessary to pay the buydown payment just to have lower payments in the first two years.Additionally, my lender said that if I refinance before the 2-year period is over, the remaining buydown payment would be applied to the principal.

The borrower can pay off the remaining principal balance, unpaid interest earned, legal fees, etc.

Given that I've been able to find brokers willing to give me a HELOC off my primary residence with a fixed rate are there any drawbacks of using a HELOC instead of a conventional loan vs a home equity loan? 

Depending on the facts and circumstances of the agreement, it could either be treated either1) the sale occurs as of the original agreement date, and then your taxable gain is generally spread out over the life of the principal payments as an installment sale (although I should mention any depreciation you've taken on your property could affect this), or2) the sale does not occur until the lease option is exercised, and gain reported at that time.

Seen a YouTube where the owner/principal provided a process to scale quickly.

Thanks you for sharing.Question, as I pay down the principal on the entitlement, does that me the entitlement goes down too?

When you can buy properties like this, you can get almost 100% of your money out of the property, convert the property into a long term rental loan, with a DSCR Loan (Debt Service Coverage Ratio) where we as the lender look at the property and if it cash flows, and that is expressed as a ratio, for instance if your Total Loan payment including Principal, Interest, Taxes and Insurance was $1000/mo, then you would need a rent of $1200/mo and you would have a 1.2 DSCR Ratio.Here is an example of a cheap duplex https://www.zillow.com/homedetails/732-Broad-St-Menasha-WI-5...