That flux drop might actually make Storm Needlers Onslaught viable. Well, enough to at least fit one.
750/650 =1.15 damage per flux
500/350 = 1.42 damage per flux
A 23% improvement in flux efficiency while still dealing out large mount damage, since 500 kinetic DPS is still more kinetic DPS than any other single weapon.
Interestingly, from my damage per OP plus vents method, the efficiency drops very slightly. 750/(28+65)= 8.06 versus 500/(28+35) = 7.93. Keeping the OP at 28 while cutting the damage by 1/3 hurts efficiency from that point of view, although not by enough for anyone to really notice.
Basically, what I'm saying is 2 old style storm needlers + 28 vents (84 OP) is slightly better than 3 new style storm needlers (84 OP).
1500 kinetic DPS at 650+650-280=1020 flux/second versus 1500 kinetic DPS at 1050 flux/second. Need 1 less mount, and have 30 better flux dissipation for the same OP cost. On the other hand, I don't think there's a capital ship with sufficient spare vent capacity and sufficient large mounts to actually prefer the old style, except maybe the Conquest.
Interestingly, this is a lot like the plasma cannon buff. More efficiency but weaker per mount, along with less penetration.