There are a number of different beam ship philosophies.
Parasite battleship/destroyer whatever you call it. Maximum boost engines, perhaps maximum sized for fuel efficiency. Speed is king. No turrets needed. Against some enemies, the enemies will have reduced accuracy if they haven't turreted their main guns. They can either hope to win by absolutely outranging the enemy if they have a tech advantage, or by having a shielding advantage, they come into range, fire, and withdraw out of range again and let their shield regenerate.
Sluggers, designed to be fast enough to close with the enemy, and tough enough to survive doing so. A slugger fleet will incur damage and casualties, but they close to a range bracket where they do more damage than the enemy. Maybe they have a higher dps, or they have a huge burst from reduced sized lasers that they fire at point blank range. As they have to close within enemy weapon range, they generally do not have the time for shield regeneration, so shields would be minor compared to armor. Expect your fleet to be in repairs for a while after the battle, but hey, you get crew grade improvement from taking damage!
Swarm, (no longer as practical with the meson changes), philosophy was that the enemy couldn't split its fire and reliably kill all of them before they did damage.
Beams as support. You have a couple of beams on all of your capital ships, so as to have the ability to finish the enemy after. They exist to prevent free kills by the enemy and to save ordnance.
Point defense ships. In ship to ship combat, they deny the enemy the opportunity to do point blank damage with impugnity.
The Absolute is absolutely a cruiser role. It can reach almost any point in a typical empire without refueling, and possibly without needing refueling to return. That is a pretty long range, and comes at the expense of top speed. If you want a fast responder that can shift to any part of the empire quickly, or can check out the frontier, this can do the job. Whether it can handle the problem once it gets there is a different question.
It can also serve as forward picket for a substantial period of time. In VB6, I preferred using carriers for long endurance picket, because the parasite craft could have the speed advantage over any enemy, while having the endurance of the carrier.