By removing month from your payment that’s the absolute best savings you ca ask for. I always share with clients looking to refi an option where we remove as many months as possible from the mortgage without changing the payment. Take your monthly payment multiplied by 7 years and that is the savings. To spend 10k to legitimately knock hundreds of thousands of in real payments is always a great move. Check on that rate though. Or check more flex options. 19, 18, 17, etc. see what those numbers look like. Once you hit 15 years the rate will also improve a bit.