Where I live for the cost of doing so it is cheaper to buy new multi family 2-4 units and then earn 3X-4X the rents for the same cost.

We paid them 9% interest (they put a private mortgage on the property) and give them 19% membership interest in the holding company LLC How did you add value to the deal?

None of these originators are allowed to assess you as a higher risk because you paid off a mortgage early. 

Doss Docs are cheaper than Lightning Docs from Geraci and they can cater to junior lien positions and cross-collateralizations, too.

minimizing free cash flow with larger mortgages or shorter term mortgages takes the cash flow which would be taxed and puts it into the amortization of the loan. 

Yea thats what i have found out. but i have a hard time scaling since im not able to cash flow. it becomes difficult to keep adding more properties when you have to cover the gap in rent vs mortgage. 

Here are my thoughts about your decision to refinance.Process:Understand your current loan terms.Check your credit score.Compare offers from different lenders.Get your property appraised.Submit your application and go through closing.Considerations:Current interest rates vs. your existing rate.Amount of equity built in one year.Closing costs and fees.Your long-term financial goals.It's a complex decision, so consulting a financial advisor or mortgage specialist might be helpful.

There are also millions of households of undocumented individuals holding mortgages.

., Honesty is the most important aspect in mortgage lending. 

If your goal is to offset your mortgage with a house hack then Lowell would be a good bet, but if you're looking for a longer term appreciation play then the areas closer to the city would be better, although the offset from cashflow may be lower than what you're looking for.A good step for you would be to dig into specific areas more as @Lien Vuong noted above.