I think the mixing may be wrong, but i'm not sure, i've never worked on anything with so much going on, so i'm not too sure. I spent a good amount of time tweaking some presets in Sylenth1 to kinda get my own sound out of it, which I think I was fairly successful, and I didn't really mess with the percussion because I was lazy.
It's a good composition, but the sub-bass seems a little overpowering in parts. Maybe try cutting out all the frequencies above 100 Hz in your sub. At the same time, make sure that your other instruments aren't lower than 100 Hz. It'll help your sub sound a whole lot cleaner. Also, maybe cut the volume down in your sub. It's meant to be felt, more than heard.