Elk are big critters, with big(ger) kill zones and the temptation to stretch your range on them can be high. Thankfully I've never lost an elk, but I've been on a few track jobs that didn't end well and the ringing similarity in all cases was a "marginal" hit.
Personally, and bear in mind I've only shot a few, I try to keep my shots low, in the bottom third of the animal. This shrinks the kill zone for me a bit to where what I'm aiming for is the same size as a deer's kill zone.
If you are really sure your going to put the arrow where you need it, fire away. If your not certain, hold off.