I'm gonna rant a little about SC and BaB survivability.
Having 6+ armour basically doubles 5+ armour survivability against armour hitting weapons. This is not so against weapons with re-rolls however.
A SM killing fleet will most likely have about half armour ignoring weaponary. Eldar can get excessive numbers of armour ignoring weapons but for most fleets the above statement holds true.
So with a +50% damage effect you've got an equivelent armour 5+ 9 hit ship with 1.5 shields. As weapons batteries will usually be the first to hit a ship we can transfer some of that staying power into the shields, so 8.5hits with 2 shields.
Now certain every day game effects will scrape off a hit regardless of armour. Criticals for instance will do this. This will reduce the worth of armour, but not by too much say -0.5 hits, leaving you with a Chaos cruiser!
A 10 hit BaB wth 3 shields would be an equivelent armour 5+ 14hit monster with 5 shields! (conservatively)
Now you can get really lucky and kill a SM ship with fewer attacks, but that's the horrible drawback of having elite armour. The up side is that they will have fewer chances to cause crits!
The law of averages will on the whole give you Chaos cruiser tough Strike Cruisers and Planet Killer tough Battle Barges. However when the enemy is lucky you will feel it more. That is the nature of the SM fleet.
Now a rant about formation:
The BaB can sit back and look pretty in it's own formation offering little extra SCs could in its place while the strike cruisers get to grips with the enemy.
This is just pointless! So what if it's got much better survivabilty than a SC, if it won't get shot at anyway as the SCs are more of a pressing concern and far easier to neutralize. The BaB wants to be in there with the SCs using its BCs as close as possible, or hell maybe even boarding!
This isn't a BB that can sit back at range and be valued in a supporting role. It doesn't have the range and it doesn't have lances or other range ignoring weapons (at least no more than SCs could offer in its place).
The BaB isn't only slightly worse at turning than its accompanying cruisers like a Retribution or Desolator. It is horribly missplaced in a fast and manuverable fleet where it will be left behind to rot, or will drag the SCs and escorts back with it into a slower and more predicatble course.
A point that fixed and then broke again was the almost pointless 'extra' TH on the BaB over the SC having 3 over 2 usually means you really kill one escort or get an extra fighter. So I'm gonna make the BaB have 4TH's/8Torps.
Cheers,
RayB HA