I'm well aware that I'm changing nobody's position on this but if you arent taking the shot with a mechanical because of the elk's position or concern about hitting bone then you have no business going for that shot with a fixed blade either.
If anyone thinks that they are blasting through elk shoulders with a fixed blade I can dig up some photos that say otherwise, between guiding, a shoulder hit elk or two myself, and about a half dozen broadheads found in shoulders of elk that appeared perfectly healthy when shot much later I think I have a decent level of experience to say that a fixed head has little to nothing to do with getting through the shoulder, most of the time your broadhead is just exploding, no matter how tough it is...sometimes you get really lucky and shatter the whole bone or blow right through it, I've seen this a couple of times, both happened to be Rages, never seen it with a fixed blade FWIW... I personally don't have anything against fixed blades, and carry a tough single bevel that hits the same as my rages to use if I know it will be a short shot with no wind... however shots on elk tend to be windy, or you are in a less than optimal shooting position and torque your bow, or a multitude of things where forgiveness in arrow flight is helpful. for the most part I grab a Rage and go with it, FWIW the two toughest tracking jobs I have had in 20 some odd elk were the two I've shot with fixed blades...