Have tried the frigates in battle, and they proved themselves very useful. Might be in part because was using the new transport figures for them, which are tiny and look harmless, cute even, so they didn't get picked on as much as they should have done.
However more seriously, the twenty damage actually makes them survivable against direct hits from battle level ships (assuming no outrageous beam rolls). The beam was also functional.
On first look at the dreadnought I was more impressed with it than most people here seam to be. For me it was a specialist role varient designed for long range destruction outside of discharge gun range.
Not necessarily as useful as the HC in all circumstances, but more durable and with more firepower at long range, these all seamed like reasonable trades considering the HC is one of the most powerful Arm PL ships out there, so a varient almost had to be less useful. Haven't yet had the chance to use it in the sort of fleet battle it's intended for, but hope to at some point.
I agree with others that the Vorlons need a carrier, just to get some fighters on the table as without them you really suffer from enemy fighters. Logically it would be a cruiser hull for the internal space to provide full fleet carrier capabilities to the fighters, and why wouldn't the vorlons make a fleet carrier if they were making a carrier at all.
However the Regeneration SA is totally useless. The only reason for taking a SA to increase your self repair rate is if the ship is in danger of dying, very soon. being adrift and unable to fire will mean that it will die, as it wouldn't need the regeneration SA if it was somewhere safe to begin with. About the only change that would make the SA useful would be if it got a normal turns self repair in the movement phase, when it declared the SA, and then got it's NORMAL self repair at the end of the turn.
Only then would the penalties of no firing and adrift under the guns of the enemy perhaps be worthwhile. Even then I'm not sure the difficulty of the SA shouldn't be 8 rather than 9.