Simon, allow me to share a very pragmatic tip: always keep your target audience close to heart when considering feedback.
ViC offers a tremendous repository of info/expertise from a community of gifted musicians to help hone your sound - mixing, production, etc - and it's always good to get feedback from other musicians as a balance... but the reality is that the general public is listening with a different set of "ears."
This is particularly true in this specific circumstance because you are in a position to get feedback directly from the MMA crowds and community. Just like comedians when honing their material, take it to the people, to an event. Mingle and get feedback from viewers/listeners. Trust me, they'll be more than willing to offer their opinions. And if you're single... well, all the better, lol!
My guess is that they will love the guitars/power chords mixed with the symphony - a little grunge with class. Maybe some big Taiko-style drums, etc. But what do I know? I'm not in the MMA scene, and I definitely do not listen to what most others do.
You're demo sounds good. Now let your listeners help you out.