I would expect you keep your personal progress for the goodies, and the guild progress for your participation is locked on the maps/championship for the guild you leave. I presume that once you joined the new guild you gain the guild progress of it on the QI championship ranking but you will have to gain again at least 160 progress to be eligible at the end of the championship for the final reward. I also presume, to avoid abuse by guild hopping, you aren't eligible anymore for the championship final reward from your previous guild you left.