my 2 cents almost 40 yrs of bow hunting experience)
BOTH broadheads work JUST fine when you place them where they should go!
typically folks go to mechanical heads due to they fly better in MOST all bows without any issue's
where as FIXED heads, some times can be more finicky on bow's, meaning NOT all fixed heads fly as true in bows, you have to many times FIX a broad head that fly's from your set up, and or you need to tune your bow to get them to fly rue
paper tuning things is a IMO a very important thing when shooting any arrow/broeadhead set up, to know your bow is in tune and working as best it can ,
but even still, when a bow is 100% in tune, some fixed heads do NOT fly true, some need you to adjust more for them, this is exactly why there are SO many different designs to fixed heads, every maker TRIED to make a design that would fly true to EVER bow
yet IMO, there are ZERO designs that do this 100% of the time!
the only one's that come close to being able to fly out of every bow, , is SOME of the mechanical heads
when thinking of heads , maybe think of this
fixed heads tend to be stronger and as stated above, less to go wrong! and IF left INSIDE a animal, they will more likely do more damage as an animal runs, walks and moves in general,!(as many mechanical s when they are in a animal have edges or blades that can fold back in , or can even allow an arrow to back out, due to blades can close back up sort of, allowing arrow to come out easier than a fixed head )
thats there main advantage!
BOTH can be deflected if they hit something in mid flight, and or hit bone, there is NO magic head that goes thru things period!
angle,. speed, and other variables come into place, that can effect the path in which either fly at!
I have killed many many deer with both designs, I personally prefer GOOD mechanical these days due to how much easier they are top get to fly true, MEANING they fly the same as my practice arrows with target tips( this is a BIG part of bow hunting, having your target arrows fly to SAME point of AIM< as your broadheads, MANY fixed heads again will NOT do this, they will have a SLIGHTLY different point of aim)
when your hunting deer or most any BIG game animal, your aiming spot is NOT at BONES on an animal, your aiming more at softer tissue to get into vitals, so when you DO your part right, hitting bones isn;t normally a issue to worry about
BUT when things go wrong or off target some, this is where ANYTHING can happen
Fixed heads MIGHT have a small advantage when things go wrong, due to , there stronger, no moving parts, and can stay in an animal better!
but I still prefer an arrow to fly's better to lessen the odds of that off target shot placement!
but BOTH again work well when there set up to fly true to YOUR set up!
something else to keep in mind, is making sure your bow and arrows and broadhead's are all of proper weight for things for YOUR set up
to work well together!
if your not sure, ask a good local bow shop about YOUR set up and math all things up, to get you the best possible set up!