I played a game at the tournament using the Federation new light dreadnought, and a very nice ship it is. I took a DNL and a Wolverine against an Orion fleet composed of an Ok6 (ph-g in the nose, photons in the wings), a Salvage cruiser (photons) and two Light Raiders (ph-g in the nose, ph-1s in the wings), and quite convincingly won.
The light dreadnought is a hunter. You strike an enemy fleet, cripple a ship with photons and then move away, finishing off the cripple with long range phaser fire or drones. With fast and All Power to Engines, you then evade the enemy, using terrain or simply distance, and reload your torpedoes and recharge your shields.
After blowing through the enemy formation a couple of times, you've done enough damage to move in for the kill.
In the battle I used terrain to circle the Orion fleet, which was unable to catch me, and first eliminated the agile light raiders, which with an all phaser armament, could All Power to Engines every turn in order to catch me with no reduction in firepower. Once these units were eliminated (with the loss of the Wolverine and quite a lot of damage inflicted on the Ok6) I then moved in behind the adrift Salvage cruiser (don't roll 1s on your HETs kids) and chewed on it with my phaser suite till it was crippled, and a further tussle with the Ok6 resulted in that ship being crippled.
In small games the light dreadnoughts will do very well, particularly in concert with the fast cruisers, slashing through the enemy force, crippling or destroying a key ship, and then running away to reload and recharge any shield damage taken. The prospect of fast fleets led by light dreadnoughts, particularly if fast war cruisers or destroyers are added, is a very interesting one.
The miniature for the Federation Light Dreadnought is very nice, and I'd recommend getting your hands on one for any Federation player. Partner it up with 2 Manta Rays in a 750 point fleet and see how it feels. Remember it isn't a brawling fleet like Gorn, but a surgical fleet. Don't fight unless your ready, use distance, and when you need to reload and recharge, All Power to Engines away and do so. If you get a couple of solid blows in early, each strike faces weaker opposition.