A sad affair, but air-racing of this nature is always going to be inherently dangerous, and I don't agree with the Aero GP formula of close racing near to relativley highly populated areas. How much worse would this have been had a by-stander been killed?
The rival Red Bull formula, with aircraft manaeuvering around a course as a time-trail has so far proved popular and spectacular whilst being a much safer idea.
Add to that the fact that the Extra has around a 30Kt advantage on the Yak 55, and thus any real racing is not going to happen, and I feel this was a predictable tragedy.