There's another option for people who are scared of uncertainty of adjustable rate.
Penfed Credit Union has 5/5, which adust every five years. For example, rate adjusts after 5th, 10th, 15th, 20th, and 25th year only, not every year after 5th year like 5/1.
The interest rate can go up maximum of 2% every 5 years and the cap is 5% above the initial rate which is 3.25% with 0.5 point right now. The rate is good and the Jumbo loan has the same rate.
I did some calculation and it would take 14 years to break even for the worst case senario for following condition.
$500K loan 3.25% 5/5 loan vs 5.125% 30yr fixed
https://www.penfed.org/productsandrates/mortgages/mortgagerateslisting.asp