OK, I'm not sure I follow here. What benefit is there to doing this?
Forcing hit allocation. The rules for squadrons state that if a squadron is going in more then one direction (away and abeam, for example) then you have to choose which direction you wish to consider them moving. However, hits can only be assigned to the ships moving in the chosen direction. Since Explorers have weak rear armor, it's more favorable to fire on that, so, the trick is to have only the ship with the most hit points expose it's aft while the others try to present their abeam profiles.
Weeell, 4 Carnage and 2 Styx (at 1240 pts total) would utterly annihilate the Fortress Monastery. I mean, it's not even pretty. Sure, it outweighs the FM in terms of points, but the FM doesn't come close to winning this duel. If it were only 1 Styx then I'd suggest that the FM would eventually win, due to insane number of hits and favourable special order rules, but as soon as you cover the AC gap then the cruisers win. Hell, make it 3 Carnages and 2 Styx for 1060 pts and they'll still win, albeit taking a little longer. This is with the vast majority of the firepower being WBs against 6+ armour and 4 shields.
Sure, if you decide to head straight for it you'll get raped ... but it's a defence. It just sits there. If you can't outmanoeuvre something that just sits there ....
Well, actually, it doesn't just sit there, it rotates, so focus firing on a single quadrant is more difficult. Second, how do you figure that 12 lb of regular fighters and bombers = 12 lbs of thawks? (Further, at that price, you can throw in two SC, which even with the nerf , which I oppose, permanently adds 2 to the number of AC that are supported, re the thawk launch special rules for the FM. So, even if the SC are blown up, the FM will continue to treat them as if they were still present for purposes of the number of AC allowed)
And I'm trying to remember the last time I saw a carnage take a str 9 torp hit and 26wb worth of fire and not blow up.
Hang on. From what I gather you're arguing against the proposed reduction in SC launch bays right? And for this you're bringing up a Tau carrier fleet. Well, as I said a carrier variant would be added, so if you really wanted to you could bring your AC back up to pre-nerf levels. However, I don't think things are so bad for the SMs anyway. With 6+ armour and standard turrets (2/4) they're one of the few fleets that could afford to not even take any AC against Tau (not that that's possible unless there's a BB option that replaces launch bays). The other fleet being Necrons of course.
Also, as intimated above and stated by others, we're looking at a 4 turret BB. Also a 4th shield. Like the SC, the BB was "balanced" around the idea that everyone would take a fleet with a balance of WBs and lances against them. This, firstly, didn't end up happening, and secondly, even when it did they sorta still sucked.
The logic behind SMs in space is that they're tough as nails, because their cargo is precious, but not so overly shooty. This latter part they got right for the most part. It may not have seemed that way though, since the Retribution also only had 12 WBs, albeit at longer range. However, that little oversight is fixed, at least in terms of this discussion, and all these changes are just as "official" as each other, so should be considered as a whole. So, when comparing the Ret to the BB, the latter has less broadside firepower, has potentially stronger dorsal weaponry at half range which is inefficient due to interference from BMs placed from broadside firepower (and I strongly suggest this interference is kept) and slightly more potent prow weaponry. So, given the Rets increased broadsides and the BBs slightly increased prow and dorsal weaponry we're looking at roughly the same. Perhaps advantage Ret since its dorsal weaponry can add to the fleets fire on the way in.
So what does the BB get for its +70 pts? Well, it gets SM rules. We know that costs +35 pts as an upgrade. It's not worth that, but that's what it costs. So even paying full price for that, what does it get for the other 35 pts? It gets increased side and rear armour. OK, I'm fine with this, it makes sense. It may even be a little cheap. But then, why does it lose the shield and turret? It seems to me to be unjustly penalised. The point of increasing side/rear armour is to increase its survivability. But losing a shield reduces that survivability to direct fire and losing the turret reduces its survivability to AC. So why even bother giving it 6+ armour in the first place? Why not just drop its cost, keep the 4 shields/turrets and leave the armour at 6+ prow, 5+ side/rear?
The BB should get standard shields and turrets. The armour difference is to represent their extra survivability. Extra. It has short to medium ranged average firepower, with above average cost. Give it back its shield and turret, and bump the cost slightly.
The problem with that is that the damn thing becomes nearly impossible to kill in any reasonable amount of time AND it's bombardment cannon is effectively a str 8 lance that crits 50% of the time on a dorsal mount. With 3 shields and 3 turrets, you have a chance of bludgeoning it to death with a normal list. With 4 and 4 on +6, you'd need something along the lines of twice it's number of points to kill it worth of chaos. IN would just die, since it can one shot cruisers as stands and is a 20cm ship.
While I agree that SM need buffed, I don't agree to nerfing the SC because people hate the Armageddon list while buffing the BB into an unstoppable juggernaut to offset this.