Use it. It takes some getting used to but I prefer it for most general purpose knapping. The issues are: 1) Mass. Elk is lighter than whitetail or moose due its pithy core. I compensate by lashing what looks like a short billet to a T shaped wood handle and swing like a hammer, but the other way to go on your pieces is to leave them a little extra long and leave some extra material in the end. 2) Pithy core means you only have solid antler for a couple of inches past the rosette, so once you use that up, the tool hits reject stage. (As opposed to moose or whitetail, which is solid and can be used until it gets too short). 3) "Softness". I prefer to call the material "springier". It takes some getting used to, but elk will dig into a sharper platform and pull off a longer flake. That "springy" quality also makes it less "shocky".
Given how widespread elk once were I am convinced the old timers used it with regularity. If you have a supply of it, go for it. I think with a little practice and persistence you will be happy with how it performs.
Good luck,
Keith