Interesting post, TAB. I think the accident to Judy Lawson at Rangiora in 2006 could have had a bearing on the fact that only Motukarara ran trials subsequent to that.
Rangiora was closed for racing after that and despite valiant efforts from local stakeholders- who did, eventually, get trials back- racing has never been considered since then.
And- digressing - I recall an amusing chat with Viv Jack about his experience with the RAF during the 2nd world war, when undergoing flight training. At one stage there must have been joint manoeuvers with our American allies. Gosh, I said, enthralled, that must have been exciting. Bloody dangerous more like, he quipped, the buggers had all the bells and whistles and no idea what to do with it!