Thunderheads are great broadheads but a little "flimsy" IMO.
Muzzys are a little more expensive but are tougher made.

ex 1. First bow season I got a little bored one day. Had an armadillo making a ruckus all morning and decided to let him have it. WHACK> killed the dillo' but mangled my thunderhead. Bent the point and all the blades. Had to trash the head.

ex 2. Shot a muzzy at a deer and missed, hit the dirt behind it and got about 8" of penetration. Had to dig the arrow out of the ground. A rock stopped the arrow and my muzzy head was fine, just had a ding in the edge of the blade. Resharpened it when I got home and have killed a couple deer with it since. Still in balance and still flies and spin checks ok.

I take the time to tune my bow each year so the field point vs. broadhead issue doesn't bother me.

The chance that a mechanical head "could" deploy incorrectly is not another variable I want to worry about. YES they have gotten much better, but I still hear a LOT of stories each year about how a mechanical BH failed. Bow hunting is tough enough without loosing sleep wondering if my gear might fail.

IF I shot a deer and couldn't recover it, I don't want to wonder if it was my shot, or my mechanical BH that was the point of failure.

Different styles of broadheads have different advantages & disadvantages.

Fixed blades are less apt to give you an unexpected problem.
Fixed blades will generally penetrate better, and break bone better.

We all try to make the best shots possible.
But sometimes we're a little off, no matter what kind of broadhead we're using. Maybe the fixed blade is more likely to bust thru both shoulders; maybe the mechanical is more likely to drop the deer with a gut shot.

Shoot what works best for you, but don't assume more expensive is better, or that mechanicals are without disadvantage over fixed.

DM,
That tip WILL bend if it hits something hard like a rock or armadillo !

I keep my set-up very simple, fewer moving parts the better, JMO, rests, sights, everything.