Years ago the general rule of thumb, or at least what I was told was if you were saving over 1 point it was a no brainer. I am not sure that was ever really true or still applies so

First I'd ask if there is anything they can do to bring that $1400 down. I am not sure what that's for, in this case but, if you are using the same bank they should be able to wave some fees.

Second I'd look at what your new payment would be in regards to how much interest vs principal

Lastly I'd use something like Karls (

https://www.drcalculator.com/mortgage/old/ ) to put in real numbers and get yourself the best option. It might make more sense to take the 30yr mortgage at 3.6% and put the $100 a month on principal then to pay $200 more a month to get 20 year especially if you're adding additional principal periodically.

I used the calculator for years (there is a newer version) to play with my numbers. My goal was to pay off my 30 yeard in 15, 1 year in I went to a 5/1 ARM thinking rates would go down and that took my thinking from 15 years to 12. In the end I paid of my house in 9 yrs 5 months. The numbers don't lie, so plug your into something like that calculator and play with them

** Edit.. As for waiting, that's a straight up gamble and sounds like you'd have to get another appraisal so that cost needs to be factored in as well as the additional $$ you spend per month waiting