My financial models show 15% cash on cash return on a $950K investment for 65% of the equity. 

However, if it makes big financial sense to refinance within 6 months, maybe can I even pay some penalty voluntarily to make up for the loss of the original lender?

I have some financial analysis I've done to help get some tax liens in the NW suburbs where I live.  

But this scenario also gives me the flexibility to not have to do that in an financial emergency, or sock away more cash flow towards the next investment.Any pitfalls I am missing here?

Hi BP,I've recently discovered this community and am very thankful because I feel I was able to course correct my mindset before I made my first big financial decision in real estate.

Pro -  You have no mortgage obligation every month so there is no need to freak out every month  a tenant is late with the rent.Pro - You have no mortgage obligation every month so there you don't feel pressured to rush to fill a vacancy with an unsuitable tenant.Con - You have no mortgage obligation every month so there is less of a tax write off and you are more likely to pay more taxes on your rental income.

It makes me wonder if all the hype around "house hacking" and financial independence is driving the hype even higher and encouraging more millennials to jump in.

I have interest in investing but i'm confused on the financial side.

I'd prefer to buy just one of these duplexes to start out because it would be easier to obtain financially.

I don't know what your financial / investing situation is so they may or may not consider your income from real estate.