I'm excited that there's a US SteemFest in the works. I don't think that having one in Mexico will detract from the US one. There's a lot of people who can't get to the US because of visa restrictions, but anyone can go to Mexico, so I think it'd be awesome to have it in a country with an immigration policy like Mexico's.
In my view, the more large Steemit meet ups there are, the better.