Also the RT list basically says that any fleet (besides Nids and Necrons) can by proxy have any number of these as allies. Due to the fact that they count as 'transports' (given a flaw in itself.)
Ah, Plax, you miss the obvious: First, I was actually reffering to the Strike Cruiser. Though clever planning (and abusing some of the rules) can use SCs to create Tau-like storms of Thawks, it wasn't what I had in mind.
The current typical doctrine of the IN is to shy away from dedicated carriers. Chaos has access to the INs previous attempt at a dedicated carrier (the Styx) simply because of age. Ie, this is how they did it back then, they don't do it that way now, the renegades have the old stock. Therefore Chaos should be more able to bring this sort of AC more easily than the IN. It should be highly unusual for the IN to be able to outstrip the carriers of Chaos, since they've shied away from them.
You bring up specific examples from fluff of how this ship was converted to do that, or how this one battlefleet has a slightly different take on things, blah blah blah, but how we should be representing fleets in BFG is by the most typical. You could argue that variance is also typical, and I would agree. So this variance should be represented by a selection of unique or rare vessels or upgrades or options or refits. The point being that since they're unusual then they should be represented as such rather than allowed unrestricted. It may be theoretically possible for some admiral to form a fleet of Majestics and Jovians, but how likely is it? It might be true that the IN have some strange backwater battlefleet which has a completely different feel to the norm, but if you put out a list of all the IN battlefleets in the galaxy on a board and threw a dart at it blindfolded, what are the chances of hitting that list? For the most part it should simply be acknowledged that yes, there are exceptions somewhere in the IN, but we're just using mainstream elements to represent the feel. You want something else make some UHR and play it. That represents the "rare" element fairly well I should think (the more liberal opponents that allow it representing the more liberally viewed sector authorities that allowed divergence from the norm).
I don't mind making a set of standardised "official" house rules. A pool of ships or rules or refits that specifically require opponents permission to use. For example, the Nemesis or Ark Majestic could have its stats made, balanced, ratified, etc and then be put into this category. So players everywhere will have the same notion of what a Majestic class is, but its use will depend upon the opponent and therefore it won't be an automatic inclusion for all IN fleets. So, in other words, rare.
Again, here's the thing Sig, you assume that the three lists we have are 'typical' (Gothic, Armageddon, and Bakka) however, all three follow very different strategies. Armageddon favors the Torpedo and Lance and eschews NC. Bakka eschews AC for guns. Battlefleet Gothic, being the game's namesake, gives a list that leaves out quite a few ship classes named in it's own bluebook fluff, in favor of presenting a generic list that has little to do with the actual battlefleet's roster, but rather is a sampling of all the ships that took part in the Gothic war, including those that came in from other sectors. For example, where is the Relentless class cruiser?
Hell, from what we know of Segmentum Obscurus, it's not unknown for IN to still be using Chaos ships, since 'modern' IN ships are actually pretty new. The most common, baseline, current IN cruiser, compared to it's battleships, frigates, and grand cruisers, still have that 'new ship' smell. Hell, the ships ofthe Gothic ecotr, given how short a time beforehand that the hulls we have dates for went into production, would have been, by the measure of such things, Brand spanking new. Considering that the Mars is the very oldest of the 'Modern' cruisers and BCs, and is a hybrid carrier, I find it odd that there are not more carrier variants out there, since it predates the Gaerox Incident by three or four millenia.