This is a pretty epic piece, I must say. You have some good ideas and your musical pallet is fairly developed. One suggestion I may give when writing orchestral music is try using some tempo changes and dynamics. The piece is great as it is but adding some more powerful dynamics (You may have written some dynamic changes but it's difficult to tell over Sibelius Midi) and tempo changes can bring life to a piece. Over all a great work and keep them coming!
Thanks :). Yeah, there are a few dynamic changes in there, but, as you said, Sibelius made it hard to hear them. I'll keep it in mind.
Please contact me if you would like to use this in a project. We can discuss the details.