KMD, while I have no experience hunting Elk, I do have a fair amount with Red deer, they both share the latin name cervus elaphus, and will interbreed quiet readily.
In my quest to continually learn about my quarry, I am constantly reviewing my methods and changing tactics as I see fit, an open book if you like.
Rather than bugle, Red stags roar, and I mean ROAR, they make a Brahman bull sound like a fawn. Reds are very aggressive and I know of areas in NZ where Reds begin to out breed Elk simply because the Red stag will dominate the battle, even though he is a much smaller animal. My concept here is, that I am going to give bugling a try and see if it will fire up the Red stags, it may work better than Roaring. Here's link.
http://www.youtube.com/watch?v=97ORGksHhKw
Anyway, where is all this going, well I have started to read up on bugling tactics used by US based hunters, and there is a wealth of info out there.
A book I am reading at the moment is 'Elk Talk' and it will probably answer a lot of your questions.