So right of the bat, I'm enjoying the feel. It's still fairly dark and menacing, but it's got more of that "serial killer clown at a haunted amusement park" kind of menacing vibe to it, which is pretty fun. The arrangement is definitely solid, so I don't have much to discuss on that front. Solo writing on the steel pan and trombone are especially high points.
You're right about your initial concerns regarding mixing, though. It's a little too tough to make out the drum parts for my taste. In particular, the piano tends to overpower them even when it's playing a background role (for instance, early on in the first statement of the A-section theme, when the piano is just playing that reggae "bubble" chord pattern, it's a little too much in the forefront. Reggae is a very rhythmic genre, in my eyes, so drums and bass should probably play a more prominent role in the sound, even with the more jazz-styled arrangement you've gone with.
Additionally, if you can find somebody to play those horn parts live, I feel like the quality of this track will improve by an order of magnitude. The writing is so solid, but I just can't get past that "uncanny valley" feeling I get from the trombone.
Seriously, though, keep up the work on this one. It's super good.