a major discovery has been made!!
a couple of minutes ago, it hit me that it may be possible to do a jH after entering flight mode rather than a jM. surely enough, it works. my bnb is now:
cLMH S jH airdash jH flight jH (airdash jH) x6 /flight jH sH hypergravL 1hypergravrep sH S jMMHS
546,200 meterless from anywhere
this combo is composed entirely of fierces. in other words, i am fairly certain it is impossible to come up with a better non-corner combo unless someone finds a way to incorporate S/jS
edit: I’ve been able to improve this even more; this time reaching 567,100 meterless from anywhere
this one is legitimately hard, however, and not nearly as reliable as the first.
as i was saying earlier, the 546,200 combo could theoretically only be improved by incorporating S or jS into the combo. i went into the lab just now with the intention of doing just that. i started the combo with a single rom loop (sj up and towards them, jH, airdash down and towards them, jH). then i S to relaunch, and here’s where i hit a wall…
after the rom loop/S, if you jH airdash (past them) jH flight and then try to jH, it won’t connect. so instead, i tried to superjump immediately past them and jH (using the back part of jH’s hitbox because i am on the opposite side of them). then, i activated flight using the reverse method i spoke of in the OP. the jH afterwards connected!
for this combo, you can’t jH below them, then easily airdash past them, jH them again and do reverse flight. you have to go past them with the initial superjump (well, the second one because you’ve already done a rom loop) and reverse flight after the very first jH. it is very hard to connect the jH -> airdash jH’s afterwards, but it is possible (you can verify this by doing the combo in the corner, which is fairly easy).
here is the combo:
cLMH S sj jH airdashdownforward jH S sj(behind them) jH flight(reverse) jH (airdash jH)x5* /flight jH sH hypergravL 1hypergravrep sH S jMM**HS
*airdash jH 5 times, not 6. if you do it 6 times, your hypergrav loop afterwards won’t connect and you will do less damage overall.
**if you’re going into supers afterwards (i.e. wesker assist -> hypergrav H -> tempest), try to only do jMHS to end the combo. the second jM makes for more damage if you do a meterless combo, but it will scale your supers afterwards if you choose to spend any and lead to a net loss in damage (the first jM is still necessary for suspending them in the air for long enough).
567,100 meterless from anywhere
edit2: forget everything I just said about the 567,100 being difficult because of the superjump in back of them -> reverse flight thing. turns out you can just do the single rom loop, S, sj and jH immediately, go into flight, and link the H’s afterwards. no going behind them/activating flight mode in reverse necessary. no jL necessary to connect the jH’s after the flight. this is actually pretty easy to do consistently.