Checkin it out now- Sounds pretty sweet at that speed, though it almost feels too rushed to be used as a main overworld theme in the darkworld
It'd sound sweet though if it were used in the same context as the Death Mountain Dark World theme (faster, darker, etc).
I must say tho; I'm glad I added the portamento to the last section of the Tal Tal Heights theme just before the switch to the Dark World break. It adds a bit of flare.