First off, people really need to read this and be clear:
There are NO TA novels. None, zip. It is hard to take critics seriously if they cannot inform themselves about the most basic bits such as the existence or non-existence of any novels (note: any, not a specific one). The Galactic War reports are direct Cavedog publications published online through their online Boneyards service. This is not a case of some company farming out novels to a third party publisher/writer, but the actual company releasing articles directly. It is equivalent to as if GW released fictional articles on its website (which it did do previously). The IP holder is the one that determines whether something is official or not. Not the original designer if they leave. The original designers for 40K have all left GW (yes, even Rick Priestley). Are we then to conclude therefore that nothing GW releases can ever be canon again just because the original designers have left? No, because GW still holds the IP rights, and legally they are the ones that get to release things using that franchise. An ex-designer would be sued if he tried to do so.
Second, trying to expand the conflict into space is not going to be productive because there isn't sufficient data with which to say anything, other than there is detail showing the existence of TA ships and the ability to destroy and/or capture ships in space:
While merchants and visitors flee the sector in enormous deep-space craft, supplies for the valiant clones are coming in from other sectors, though in small amounts. The Core's hold over the Sector-span Galactic Gates at the entrance to Glyn is putting a chokehold on support for Glynholm's defenders.
Coming ever closer to the planet of Glynholm itself and the colony ship marooned there, the Core has implied strong tactics in choosing its fights, sacrificing one world for the gain of two. Other tactics have involved targeting incoming support vessels, monitoring their source and eliminating them from space before they can reach Arm troops. According to some of my own sources, one was carrying vital parts for the repair of the Arm colony ship, which was damaged during landing.
Arm has been fighting on a triple front here in Glyn. The majority of the clones have been guarding both doors to the Glynholm cluster, while a pocket of resistance has been tenaciously clinging to life in the areas of Dilar and Sawan'Vreal.
In an unfortunate turn, the family of Lord Glynholm was taken by Core troops during a failed escape attempt in an unmarked ship leaving the sector. Sources amongst the Core say that they are safe and happy, and that their patterns have made a lovely addition to the databanks of Central Consciousness. Lord Glynholm has been seldom seen since the news came through. http://web.archive.org/web/199910132353 ... _4-27.html
The warm orange glow of the engine burst into new life as the drive kicked into high gear. Five enormous Arm Pioneer-class Colony ships broke formation and rocketed off in different directions. Family and friends were separated, hurriedly packed into the craft as the Core closed its steely fist around Empyrrean. http://web.archive.org/web/199910130628 ... chive.html
There isn't much said at all about combat capabilities because the focus has been on the inability of support vessels and this Pioneer-class ship to escape. The key relevant parts however are in the above how it mentions Core forces focused on eliminating Arm support vessels "from space", and how fleeing civilians were captured despite trying to escape in an unmarked ship. The fact civilians were captured, rather than just simply blown up, shows the anti-space capabilities aren't just automated mines or some other automated kill everything defense. The "from space" phrase also rules out anything like a planet to space based weapon system.
However there are no details and there is no data with which to make any comparison, though 40K is also lacking in hard data regarding its ships and firepower yields. All that can really be said is that there is evidence of TA ships, and at least some of them are armed. Comparisons between the universes therefore would run into this obstacle of lack of data.
One thing however that needs to be noted, is that the cut scenes are not exactly the most accurate and be all and end all of canon, as there are certain dramatic liberties taken with the cut scenes that are not what is depicted in the actual game or background. The two key examples are the existence of only 1 barrel for the Flash tank (it has 2 guns, 1 on either side) and the Arm commander apparently starting construction of a heavy laser tower by itself (another construction unit would have had to start it, though the Commander could assist, but there is no evidence of such another construction unit in the cutscene).
Thus the constant claim of demanding a canon hierarchy runs into this issue as it is not a huge universe with a huge fanbase demanding clear-cut hierarchy. The manual and the cutscenes are extremely sparse in terms of background, and hence actually the bulk of things would lie in the Galactic War reports. However for the purposes of this discussion and at least my posts, here is the hierarchy being worked with:
1) Manual, cutscenes, and Galactic War reports of equal weight except where they directly conflict with game in which case game takes precedence (such as the 2 vs 1 barrel issue on the Flash tank, the firepower yields conflicting with lack of total destruction in game).
2) Actual in-game performance
Another such potential conflict between manual and game for example would be the so-called "Starburst missiles":
Starburst Missile: A starburst missile is fired relatively slowly at an almost vertical trajectory. When it reaches the top of its trajectory, it looks down and
locates its target. It reorients itself and fires its second stage hypergolic rockets. Accelerating at over 100 gravities, it smashes down like a meteor on
top of the target. It has a small anti-matter payload. Tactically starburst missiles fulfill the job of the old fashioned mortars. They can fire at units inside deep canyons and are effective at destroying small fast units that can foil other weapons.
TA game manual p. 52
That description is completely at odds with how they function in game. In game, such missiles are too slow to do anything except hit stationary defenses so the claim they are "effective at destroying small fast units" is not supported at all, and the units with such weapons end up being more like siege units. When it is as dramatic a difference as being good at hitting fast units and being so slow that it can only work at firing at fixed defenses, the actual game performance should take precedence. This is not as nitpicky a thing as actual hitpoints or damage number but total role change.
In short, there is background evidence for some form of space based anti-spaceship weapon system, and there is evidence for use of spaceships in the TA universe. However that is all the data available. Hence any vs. discussion would have to confine itself to a planetary based scale because once you get into space, there is insufficient data with which to conclude anything other than "both sides can have spaceships with weapons".