Alrighty then, just a heads up that I haven't read all 17 pages of this thread. I skipped to the end after the first 5. Ok, to start off with some general thoughts, I'd like to see the 2 shield 1 TH SC as standard at no points change. I wouldn't mind seeing a 3 TH SC variant (dropping the broadside WBs) at a small price increase (155-160 pts). Definately +1 shield for the BB for no extra cost (take or leave the +1 turret ). A torp variant SC is fine too.
However, the thing that I really wanted to post about is the "simultaneous" fire idea. This should not not NOT happen. There are only 2 races that the sequential fire system "disadvantages". Space Marines and Orks. I argue that the inefficiency produced by the BM interference is extremely characterful in both cases. In the case of the Space Marines, they are supposed to be inefficient in fleet engagements. If you believe that they should be allowed to fire simultaneously then this is tantamount to simply saying that they should be allowed to have lances. It is the inefficiency of the two competing weapon systems that limits SM power, not the inability to hit on a 4+ (because BCs already do this). The Imperial Navy warships do not suffer this inefficiency because lances do not suffer from previous WB fire. So this is why SMs can't have lances.
Now, what are SMs supposed to do? Assault planets right? Well, you would only need a space taxi to get to a planet. So it isn't just assaulting planets, it's also breaking defences. In particular, static defences (since they're specifically forbidden from being able to compete with warfleets). As it happens, even with the extra column shift, the combination of WBs and BCs against defences is stronger than WBs + equivalent strength lances. It's worse against non-defences, better against defences. Isn't that the perfect combination for SMs? As for balance issues, the other changes listed seem good to me. No need to change this mechanic. Particularly as it isn't clear whether it would be WB hits or BC hits that take down the enemy shields.
As for Orks, it is extremely characterful that their shooting isn't terribly efficient. Changing this mechanic would serve only to remove character from both the SMs and Orks. However, some people argue that Orks are too weak and need this boost. This isn't true. They're too weak and need A boost. This could be easily achieved by simply increasing their firepower! Moar shooty! Very Orky.