Originally Posted by cardude
Or, I could just keep the existing loan and pay the thing off in 6 years and save the 6K, but then I need to keep an extra 400K or so around when the time comes and that restricts how I can invest the money and the possible return.
That's the route I would choose.
This will allow you to see what happens to rates when your ARM adjusts in 6 years and give you the option of continuing the loan if, for some unforseen reason, the rate doesn't go up significantly.
My experience has shown spending the $6k to refinance will only insure you'll move long before your planned 15-20 year point.