Wow, condolences to all those involved . I wonder if it was mechanical or pilot error though? I've heard reports that he possibly blacked out in a stunt but also reports that he made a mayday call which would make me think it was mechanical.
He may have blacked out but not from a stunt, he was racing, and Reno racers don't do stunts, it's like NASCAR in the air, they fly left hand circles as fast as they can.
Photos taken just before impact reveal that an elevator trim tab separated, which at 400+ kias could very well cause a violent high-G pitch up as the elevator deflects so fast the pilot could not react in time, or was may have been physically unable to overcome, which could have led to him blacking out. Also in another frame no helmet is visible through the canopy, which would support that idea.
All pure speculation of course. I'll wait for the NTSB report, but that tab separating definitely had something to do with it, whether as a cause or effect, probably it's some of both.
A very, very sad day indeed. Crappy weekend for aviation all around, yesterday an RV-6 went down in a school parking lot near here killing the pilot. I almost went to Reno this year but couldn't work it out, kinda glad I missed this year now.