Ok, had a listen on my studio setup… you’re definitely on your way… wow, what a project to start on! You’ve got some good balances going here. The harmonies are very loud - that surprised me a bit - sounds a bit like Queen in those spots! Still, a different take on it - Within reason, it’s an opportunity to mix it to your own tastes, rather than just duplicate the released version.
What you might want to check with the top down approach is the amount of gain reduction happening on your busses. I can hear the transients on the drums (particularly the snare) being squashed down in the dense sections of the track, so check how much gain reduction is going on in those sections specifically.
Remember, the more elements you have going into a compressor, the more their combined level will be, and hence more gain reduction will be triggered. So even though the intro sections of the song - which are relatively sparse and soft - may be just tickling the meters, once the big wall of guitars hits, everything could be being squashed quite hard.
Generally speaking, I like to take the approach where each level of compression is only doing a relatively small amount of gain reduction. Someone once described compression in a mix like layers of clear coat on a car’s paint. You can’t just slap one big thick clear layer on and expect it to look good - it will crack up… but if you spray many thin coats of clear on, (with the right technique) you’ll end up with a deep 3 dimensional gloss finish.