The studiomaster is still looking cheap at the moment. It will manage a small courtyard. Open air in the sense of "in the middle of a field" demands HUGE power. To play to 2,000 people in a field you will want 20,000 watts.

The Studiomaster will handle the pop/rock band stuff you specify for a small pub back room up to about 150 people, so long as you do not start mic-ing the drums, but I note the band you compare with uses electric drumkit or programmed drumbeats and if you want to use electric drumkit or programmed drumbeats you should allow another 1,000 watts minimum just for the drumkit.