I wouldn't go near a stick welder for a steel bicycle frame. Even a MIG in the hands of someone not familiar with thin steel tubing is a recipe for disaster. And while I haven't had to have a frame repaired on tour, I have done my own repair a farm workshop using an oxy-acetylene set.
But seeker's idea is a good one... if you get the right brazing rods and flux. Which does add to the cost. Plus, you do have to have a bit of a clue as to what you are doing.
FWIW, my repair was to a broken DS dropout on my Fuji Touring, and it has lasted very well.