Surveying other "seasoned" bow hunters that I know personally and trust, mechanicals seem to be a lot more forgiving when it comes to placement than fixed. In my exclusive use of fixed blades I tend to agree with that, particularly when I actually helped some of them retrieve their mechanical BH shot animals. In some cases I was very surprised the animal even stopped running much less died from some of these shots.
The deer I have lost some were shot with Rage Three blade and the other was shot with fixed blade Magnus Stinger 4 blade. The two with the Rage, I did not get a pass through. One was a hit on the front shoulder and the other one hit the opposite shoulder. Trailed both for about 200 yards crawling on my hands and knees until we lost all signs of blood. With the Magnus Stinger I got a pass through but it was a little far back. Trailed it also but lost blood after a long way. Last year I switched to Grim Reapers and shot two hogs with them. One was a small sow about 50 pounds, didn't get a pass through because it hit the opposite front leg. Watched it die with in 30 yards of the shot. The broadhead broke the opposite front leg on impact. The other was a 150 pound boar, buried about 15 inches of the arrow in the pig. The pig made it about 40 yards before expiring. Blood trails in both cases was very easy to follow, plenty of blood. In both cases the broadheads were in perfect shape upon recovery. Honed them a little and put the back in the quiver for this year.