Excellent questions croz2173!
First of all, don't feel too bad about a good shot going wrong. As long as you have done due diligence with equipment selection and practice, you only attempt the shots you honestly think you can make and you follow up until the bitter end, you've done your job. Hunting is a human endeavor in an uncontrolled environment. Mistakes happen, to all of us.
Secondly, I won't lie. No matter what the ads say, the mechanical we shoot does not penetrate as well as the old Satellite TNT, cut on contact head I started with. The only problem is that it was only accurate to about 20 yards with a slow bow, and totally inaccurate with a fast bow. I've had a number of my hits with the mechanical fail to pass through. This was almost unheard of with the cut on contact. Again, I accept the loss in penetration in order to gain accuracy and a larger wound. My personal choice.
Okay, to answer your question. Yes, I have seen some deformation to my mechanical head, but no more than I saw with my old heads and never in any way that resulted in a failure to deploy. The deformation was always the result of striking bone once fully deployed. I'll share several cases from my mechanical blade use that may help:
I have spine shot three does with them. All three deer dropped in their tracks and died quickly. One required a second shot, but she did not move. The strangest of these spine shots came last year. I made a fairly level broadside shot at 20 yards. The arrow must have deflected off a rib because it angled up after impact and broke the deer's spine. Both lungs were cut and she died in moments. I was unable to dislodge the head from the vertebrae. No matter what happened, the head performed.
I have made two scapula shots. One was on a mature buck at 30 yards. He trotted a short distance, paused and turned back into range. I double lunged him at 20 yds on my second chance. Better lucky than good. Anyway, that scapula shot resulted in less than one inch of penetration beyond the bone and only a dime sized hole in the chest cavity. I doubt that it would have been fatal. At least not quickly. The second scapula shot was on an adult doe. She ran off with other does and I saw her walking with them 20 minutes later. I tracked her for 8 hours but lost blood in a standing corn field.
Lastly, I shot one doe almost straight down with a first generation 2-balde slip cam (not the one that is sold today). The shot exited at the bottom of her chest and stuck in the dirt. It appears as if the head deployed properly and there was no deformation but that deer covered over 500 yards. I lost the trail a day later. I assume that it was a single lung shot and that she was dead before I was forced to quit the trail, but I'll never know.
Now, mechanical head haters will likely use these stories against me. They seem to point to a reckless hunter using bad equipment. In my defense, there are a handful of stories out of 28 career bow kills. I realize that 28 kills is a trifling amount compared to some, but a rookie I am not. You did not ask for the specifics of the times my mechanical flew exactly were I wanted it to and I saw blood spouting from the deer as it ran, like the scene in Private Ryan. Nor did you ask about the times my shot went slightly off track but I was still able to end the day with a smile because my deer bled out and died nearby. I can share those stories on request.
No matter what you chose to use, good luck.