If an arrow is kicking you won't get the same penetration. I think you'd have to be kicking pretty bad to see a significant difference (assuming the same weight arrow/BH is used in the pentration test.)
Let's use my experiences as AN example.....
Producing less than 1/2 the FPKE out of my traditional setup - with a large, fixed blade BH....out of a properly tuned arrow (vs. the compound....utilizing mech's....and an out of tune setup that showed no signs of arrow wobble in flight....utilizing fletched arrows), my pass-thru percentage went from <50% to 100%.
If everyone who shot mechanicals would screw on a large, fixed-blade BH to the business end of their arrow....and tune, accordingly....THEN switch (assuming they were producing adequate KE) to the mechanical, we'd see FAR fewer "I lost him and these mechanical heads are junk" threads and a lot more hero photos.