Your 1500 sq home probably would rent for about $4300 a month in Redwood City (https://www.zillow.com/redwood-city-ca/home-values/). That home would probably rent for about $1900 in Portland (https://www.zillow.com/portland-metro-or_r394998/home-values...)
A $30k/year rent difference requires ~$48k more income to cover (at 40% marginal tax rates). My guess is that the 100% salary jump is more than enough to cover the housing increase (probably handles all COL difference), making SF more favorable, especially if you don't want a very large home or are quite senior.