it is all well and good saying look out, but one sunday a few months ago me and a friend flew to an airfield for lunch. The circuit was manic and as we joined the circuit on base (No OHJ allowed) the zaon soon gave us a traffic warning and I could see on the gps screen a yellow target pretty much right below us. We aborted and orbited and when we came back in we could see the other aeroplane- a high wing cessna 152 who was low in the circuit (student pilot onboard not giving good position info on the RT which is why we'd joined on base - we couldn't see him and expected him to be on downwind). It was the nightmare scenario, a low wing higher than a high wing and there was no way we'd have seen it as it was right underneath us. Likely he'd not have seen due to his wing.
That day I was glad we had the Zaon and that he had a transponder!