Just my opinion, but I believe a fixed cut on contact like the Stinger mentioned is a much better choice for a big critter like an elk than any expandable. Will they work under the right conditions, absolutely. Do you want more conditions to work with if things go bad? If yes, than a fixed blade broadhead is a better choice. I'm a Magnus fan myself and have shot the Stinger and now shoot the Snuffer SS in 125 grain. Easy to sharpen, one piece, cut on contact, extremely durable, and best of all, a lifetime guarantee. Muzzy's and Thunderheads have killed a bunch too.
Nick