As a disclaimer right up front, I am selling the Shannon mentioned. I would like to weigh in with my experience since I own both the Shannon and a Copley delrin. I bought the Shannon to start on and found it easy to play ergonomically and to get a clean, loud sound. Since then I have picked up a Casey Burns Rudal and a Copley delrin.
As far as loudness, I find that my embouchure makes more of a difference in volume than the style. I can play the Burns just as loudly as the Copley or Shannon. The difference I find is that I have to work harder on one flute over the other. Here is my impression on volume; the Shannon is the easiest, the Burns next and the Copley the hardest volume-wise.
For ergonomics I would rank the Shannon the easiest, the Burns next and the Copley the last as far as weight, balance and ease of fingering (although personally I prefer the Burns Rudal smaller tone holes).
Aesthetically between the Shannon and the Copley, the Copley is the more traditional looking and sounding. This is, of course, by design.
I am looking to move on to a keyed flute so I decided to sell one. I went back and forth about either the Shannon or Copley. I finally decided on the Shannon because, oddly enough, the Copley is more difficult to play. It forces me to be technically better to produce a good sound. I find as this stage of my playing that this makes me a better player. If I had started on the Copley, I would have struggled more as a beginner.
It has been said here, and I agree, that what flute suits you will change as you progress on the instrument and as you figure what you like or dislike about each makers style. Variety is the spice of life…