I am currently playing a "low tech roleplay" run with just low tech ships (and a few drams. That counts). I would not characterize low tech as the dakka tech or the missile specialist tech: thats midtech. Low tech is toughness and consistent missiles across every ship. Its workable without any additions from other tech levels. Sure it would be better with some other ships mixed in, but thats mainly due to those ships being excellent. The main thing that low tech lacks is a hunter frigate that can compete with any fast flanker. Otoh, it has good carrier options to deal with them, so its not all lost.
For performance: I'm still in the midgame, but 4 enforcers, 4 condors, 4 lashers, 4 shepherds can handle ~2-capital ~225k bounties.
All of the following ship reviews are WITHOUT Safety Overides: I know its good for low tech, but its a bit busted atm.
Frigates:
Lashers are workable but subpar. With AAF they have decent firepower, but between the front shield and low speed they are food for other frigates. They make for good escorts to destroyers though: the destroyers keep them safe from other frigates, and the Lashers add a lot of missile and gun firepower/DP. Comparing their base stats to Centurions is not very flattering though... could probably use an armor boost to go along with low tech = endurance.
Shepherds are excellent. A+ tier exploration and logistics vessels that have both Salvage Gantry and Survey equipment built in. In combat they are acceptable against early and even mid level (~200k bounties) threats due to their drones acting as PD screens on the initial charge and as distractions, combined with the ships tiny DP cost. I tend to install unstable injector so they can run, though it does lower the replacement rate.
I have not seriously tried incorporating Hounds or Cerberi. I should incorporate some Gremlins. I forgot about them, but they are excellent distraction ships (all the distraction of the larger phase ships, none of the ability to attack, much cheaper).
Destroyers:
The new enforcers are excellent, on par with Hammerhead and Sunders. Their gun firepower is low, but acceptable now that they get flux boosts from T4L, and they have good missile firepower. They also just refuse to die: 1290 armor with HA and AWM for 9 DP. An Enforcer with an officer can tangle with an officered capital and absorb all of its firepower for a good amount of time. Long enough for the other 3 enforcers with an eliminate order to close in to drive up flux, and then thats a dead capital.
Condors are fine. They remain unchanged from last patch; the main difference is that they no longer have to compete with Drovers which were crazy good. Now these are decent budget carriers: they bring wings and missiles for cheap (10DP). I am running 2 with Thunders to help against frigates and give EMP support, and 2 with bombers (1 khopesh, 1 piranha). Roughly the same missiles/DP concentration as Enforcers, lashers, and dominators, but backed up by fast racks: this makes them excellent at either salamander support or harpooning overloaded enemies.
Cruisers:
Dominators are good. They bring large ballistics for longer range and better armor penetration without losing DPS like happens with HVD/Mauler. They have somewhat better missiles/DP ratio than Enforcers (~3m/25 instead of 3m/27), but only take 1 officer to fill out those missiles instead of 3. While they are significantly tougher than an individual enforcer, they are not as tough as 3 enforcers (27 DP), nor do they have the same level of total firepower. In effect they are trading out toughness and tactical flexibility for (much) longer range and better force concentration (all cruisers do this). The main weakness is that Dominators have most of their offensive ability locked into their front hardpoints, lowish maneuverability, and a wide open stern: they are bad against frigates. Frigates are monsters this patch, so that lowers Dominators effective value.
Moras are good. They maintain the same missiles/DP as Condors and are a little behind enforcers and dominators. Compared to 2 Condors, they give up 1 deck, but save an officer, and bring crazy levels of toughness. Instead of being fragile carriers in need of protection, Moras are tough enough that you want the enemy to hit them as hard as they can, wasting their firepower doing nothing while the rest of your ships shoot. Especially for bombers, 3 wings striking together is potentially better than 4 wings in 2 waves of 2, so losing the deck is not as bad as it sounds.
Capitals:
Onslaughts are excellent when built correctly. Their missile firepower is at Condor/Mora levels instead of Dominators (4m/40), but its turreted letting it use dumbfire missiles very well. Their armor is the best in the game, though proportionally not that much more than a Dominator. They get even more range, the excellent TPCs, and they have a very wide effective firing arc with their guns (when built correctly) that removes the Dominator's downside of having fixed forward firepower. They have absolute oodles of free OP, so can comfortably use elite large ballistics, many hullmods, etc. A good officered Onslaught should be able to duel and win against an Alpha Core Radiant 1v1 and hold off 2 at the same time.
Legions are also excellent: They lose fighter concentration again (down to 1/10DP), but add heavy cruiser long range gunfire (plenty of flux for 2 large ballistics) and more missiles per DP (5m/40, slightly better than a Dominator). Think of them as a mora and a Dominator glued together, only for 40 DP instead of 45, longer range, an extra fighter bay, and only needing 1 officer. The downside is that they have the most vulnerable rear of any ship and are proportionally less tough than the two cruisers would be.
Dominators, Legions, and Onslaughts have a massive weakness (their rear) that the player can take advantage of to quickly pop them with fast strikers or phase ships. But the AI is not the player! As long as you protect their rear via orders, fighter commands, escorts, etc etc then this is not an issue.