I did the same math comparing portland with suburb schools (around portland and seattle) and came to the same conclusion. But one other thought is when the money goes to the mortgage, you get to keep the wealth after (assuming you sell to downsize at some point).
Yes, good to do the calculation properly before making the decision if its motivated primarily by finances; sometimes the outcome can be surprising. Ironically speaking specifically about Portland, you'll pay _less_ in taxes moving to e.g. Washington schools in addition to getting better schools. But I think this is likely a special case.
More money in the mortgage principal you theoretically keep when you later downsize housing, but you also will probably spend a good bit more in taxes as well.