At high altitude, I blip the throttle from full, to idle to full. There is about a 2 second lag, so, at 1000 FPS (roughly) the plane is about 2000 feet high. But the plane is barely within my ability to control it at this altitude. I think 400-600 feet is about the limit for a normally sighted pilot flying a 60"span model.

We fly from a full scale airport here, about a mile away from the main runway. We usually monitor the unicom frequency for our airport, and if not, we usually can hear the full scale guys coming in. When we do, we get down low in the traffic pattern.