Really? It's a relatively small target that's impossible to hit from the top. And those slash beams would have to take out that LRed fast; aren't the Lilith's turrets more durable than usual as well, given the Lilith's notable durability for a cruiser?
The beam turret is impossible to hit from above. Ok. Can't fire at targets above, either. So the angles from which that turret can't be hit are the same as those it can't itself cover. Explain how that's a strength.
That turret isn't small either. If you can see it, it's actually quite easy to hit, especially from the bottom. A Sobek will kill a Lilith quite easily in 1v1.
The Lilith maneuvers to give its LRed just enough of an angle to fire on its target. As soon as the beam shot ends, it maneuvers back so that the LRed is impossible to hit (being covered by the rest of the ship's hull). Rinse and repeat. Not fool-proof by any means, but it just tips the balance more in its favor.
Either way, the *best* case scenario is that the attack-oriented corvette with heavy anti-warship firepower disarms the Lilith's LRed before its health falls below 45%. Assuming the Lilith isn't able to jump out before it eventually gets destroyed, that's still a single, small cruiser giving a powerful, heavy-firepower corvette in its intended role a serious thrashing, by itself. No other cruiser in the game comes anywhere near that level of performance, and for good reason: it's like mounting a BGreen on a Leviathan--it's hugely disproportionate firepower for its size, type, and design.
I've always found the Lilith's LRed to be very dubious. Their Finest Hour is notorious for its major...errors, intentional or not, that really distort the performance of most ships present. The Colossus is completely unable to move (then how'd it even get there in the first place?), none of the Allied warships are allowed to use their beams because the beam-free-all cue comes just BEFORE they show up, and the *only* Lilith in FS2 appears with a beam cannon so powerful that it makes the Ravana a master of shock-jumping despite mounting only two of them and being a glass cannon in general--is it not possible that the only Lilith in FS2 was given an LRed for that mission so that it could 'clean up' the allied cruisers before the main focus of the mission (the Colossus's final battle) comes into play? Isn't it rather odd that the Lilith's tech description (not to mention its references in the rest of the game and mission) makes no mention of a heavy, destroyer-level beam cannon, but goes into detail about its incredible armor?
To me, the Rakshasa feels a lot more like the ideal, iconic Shivan cruiser--heavy forward firepower, modest point-defenses and durability, and entirely attack-oriented. Its firepower of 3 SReds is notably dangerous, but it doesn't scream 'a small cruiser-sized destroyer, sans fighterbay' like the Lilith's LRed.
With regards to the Hyperion: yes, the SBlue is a notable improvement over the SGreen; I'd say its best distinction is that it's a viable, light anti-ship weapon--whereas the SGreen isn't really good enough to practically serve in that role. To be honest though, if it were possible to swap out the SBlue's in order to upgrade the STerPulse turrets to TerPulse turrets, it would probably make the Hyperion significantly better in both the AA, escort, and supporting anti-shipping roles.