Porto Allegre is as good as Rio or Sao Paulo. Maybe better.
But I worry this may be a mistake fare since all the others are like $1500 at least and I'm not counting on Copa honoring a $150 fare.
Also getting to Cancun isn't a lot less on points or money than just getting to Brazil straight without all the traveling for days.
I played with this for a couple days and finally decided it's better to just wait for a $450 fare straight to Brazil.