Big nasty, you will not regret your decision. The mechanicals are a novelty item in my opinion. A solution looking for a problem that can be fixed with a modicum of tuning. If your fixed blade broadheads are failing it is because you bought a piece of junk. If your mechanicals are failing, well you might want to look in the operators manual. I have heard more stories of how the Gee Whiz Dyno Wing 2000 with Astro Sprinkles, has failed to deploy its super dimensional hyper phastic blade pack than I care to. It seems the key is to have a video crew and a source of free Gee Whiz Dyno Wing 2000 with Astro Sprinkles.
From invading Mongol Hoards through English Longbowmen, right up to our own American Indians, there is nary a written documentation of a broadhead failing to open up inside the target. These folks built pyramids, sailed wooden ships to distant shores, invented metalurgy, but didn't feel a need to make a poorly designed broadhead. I have it on good authority they were pretty danged successful at killing stuff too.
Just something to ponder.