Depends on what elk sounds you are trying to reproduce. For bugling and higher-pitched cow/calf talk, I prefer an uncut reed call, and thinner material doesn't need to be stretched as tightly as thicker material. If you want to save some material in your call making, try this: take some turkey calls you have already made but don't use and pop off the ends of the reeds with your fingers. Often doing that will produce a call that will make an excellent bugle...especially for reaching those high notes.
Good bugling often requires a call that will ascend to the high notes easily combined with using your voice on the front end to make the initial growl you need before ascending into the high-end notes with the call,...and then dropping back off into the end grunts by again using your voice in conjunction with the call.
for lower sounds,....older cows, and bull growling/grunting,...a little heavier material may work better, and with some cut variations. You will have to do some experimenting to find what works best there.