I haven't considered a 15 year cause my goal hasn't been to speed pay-off the house. The payment would be $1900 or more. Income is high/steady now but it may not be in the future, which is why the extra payments are appealing as an option (but not a necessity). My approach has been to power stash when we can, and have pretty minimal expenses for the times we can't.

If I look at the math another way - the true cost of my current mortgage from today (if I make no more extra principal payments) is 451,975. The true cost of the new mortgage (option 1) would be 458,282. That's only a difference of $6k. Looking at the amortization schedule, the first couple years of the new loan have an interest rate of about $800/month. So, I'd only have to make an additional principal payment 8 times before I'm on par with the other loan (very do-able - on these good months, I might make 2 additional principal payments). I could see if I was 10 years into a 30 year loan, refinancing to another 30 year could be costly in the long run, but I'm only 3 years in (and 1.5 years ahead of that in principal payments).