I'm constantly juggling the rates for my Airbnb listings based on what my competitors are charging. 

While they might not be the cheapest - no HM lender is "cheap" - they do a good job at what they do.

What is your current rate and what are you being quoted?

The entirety of these cities aren't just comprised of cheap run down properties. 

I think most investors want to win on more than just the interest rate.

That is tight leverage for an investment 2nd position loan.A private investor might be willing to do it, it's not going to be cheap at all & will be short-term money & will not be a line of credit to take out at your liking.What is your rate on the 1st?

If someone offered to finance this house to you at your current rates if you put down $250k would you do it?

Am I being cheap?

I was hasty due to the higher mortgage rates, and it turned out to be a huge mistake.

If the answer is yes, then it's a no brainer to make minimum payments on your 2.8% interest rate mortgage, and use the funds that you would have paid extra to pay it down faster, to either invest in more real estate, the market, or anywhere else where you can get a ROI > 2.8%.If the answer is no, then feel free to aggressively pay it down as fast as possible, to become debt-free faster, and just have a large amount of money in savings or to splurge with.The bottom line is that your 2.8% mortgage is GOOD debt.