I think it is easy to blame the broadhead when there are so many other contributing factors to the equation. Shot angle, bones hit, bow out of tune, arrows out of spine... etc. etc. If you hit the edge of the shoulder blade, the arrow is probably going to deflect with a fixed blade or a mechanical. The grizzly I shot spring of 2001 was with a fixed blade head, and we are almost certain, can't be 100%, that the arrow deflected off a rib, and went up into his shoulder rather than breaking through. We watched the video over and over and from the reaction of the bear, angle of the shot and how the bear reacted, we could tell that it did not enter the vitals.
If I had used a mechanical head (illegal but for topics sake...), I could easily blame the shot on the mechanical. I think with a better fixed blade head I could of had better results. I was using Cabela's super lazer pro mags, and switched to muzzy's after this. There were other factors that didn't help the situation, but the arrow hit right where I was aiming.
From this and other situations that I've read about, I would say there are good and bad quality broadheads out there, be it fixed blade or mechanicals. An arrow will deflect off of items like branches and leaves, so why wouldn't it deflect off bone? I think the spitfire is a very good head, and wouldn't doubt its abilities if used right. It sounds like the head held up, and did the job. After deflecting, it still was able to shatter bone?
ArcticBowMan's Hunting Photo's