I'm glad you decided to remix this song.
I like v.5 because it is more suspenseful and powerful than v.6. If you want to continue your work from v.6., I advise you to listen to Mega Man X6 intro stage song. It has an epic feeling to and may give you some ideas.
I mixed two songs, Severnaya surface and water caverns, cellos and piano only.
Original ones:
Surface:
Caverns:
"Frozen caverns" remix here:
http://soundcloud.com/rekne/frozencaverns