About to Close - Could Use Some Expert Advice

[Jeremy Dory]

We are two weeks from closing on our first investment / rental property in Denver. The interest rate of 4.3 at 15 years was locked in a few days before fed dropped interest rates 50 points. Looks like they are going to go to zero, so another 100 points this month. Thats 1.5% drop after we locked in... I want some of that 1.5%! Our credit is nearly perfect (~800) with both wife and I on the loan. If we walk away we lose our 5k deposit, but almost seems worth it to me as 1.5% is significant.

What would the seasoned professionals here do, what are our options? 

The house is new construction and we are going with the developer's lender due to $15k incentive. House (SFH) is $335k 2/2, a small ranch. A relatively good deal for Denver market. TIA!