I have shot several Whitetails & 1 mule deer with spitfire's, I have also witnessed several shot from other hunters.They do create a great wound channel. I also believe they are as good as it gets for mechs, but I haven't had near the peneration with them. I shoot a 70# bow and most of my shots are close range, I just don't zip right thru em with spitfire's. On a broadside shot at a 180# buck last fall I hit him a little far back.....Liver.....I only burried it to the fletch, should have zipped right through him with that shot. You are trading a great flying head for peneration......Its really just your choice for deer, anything bigger than deer I believe should be left for cut on contact heads.
Good hunting J