Austin does the most film work in the State, but there's tons of production that also happens in both Houston and Dallas. There's also a strong film market in Shreveport which is just a few hours away as well. Lots of corporate work, lots of reality TV, lots of TV spots between those 4 cities.
In my experience outside mixers are very rarely brought in. When they were shooting network shows like The Good Guys, Lonestar, and Prisonbreak locally they were using local mixers for all of that stuff.
Austin's a beautiful city that has grown much faster than its infrastructure has. Traffic sucks there, sixth street is great, the university is great, the crowd is diverse, and there are trees and hills everywhere.
No state income taxes, no audio unions, Texas state school board is pretty wacko, cost of living is moderate but not cheap in Austin.
bottom line: its a beautiful city, you could make a living, but you may have to do a fair amount of driving to really max out.