I actually like the look of most of that fleet. You have great "Closing" lances with an enemy fleet, and if you're playing an Imp fleet your going to cause them big problems with all those lances tearing through his precious prow armor. I always prefer the Torpedo equiped escorts (sorry, cant remember the names right now, maybe Infidel??) as they give a bit more tactical flexibility to the Chaos fleet, but each to their own.
I always thought of the Styx as a bit pricy, but since they lowered the cost its definatly doable now. The only slight issue I would say is with the MoS on your Styx your putting your most valuable ship within 15cm of the enemy fleet which is quite risky. I always used my Styx as a stand off support vessel (ordinance and long range weapons etc) as its only as tough as a normal cruiser but will give away many VP's if destroyed.
For the cost you could more or less field a Desolator Battleship (300pts) which would give you more lances, at longer range, plus the torps plus the additional toughness/hp that a BS brings to the table. My favourite tactic is to get a Desolator with a mark of Khorn and know your going to destoy anything you board in 1 turn! However this might not fit with your fluff so if youve got a plan, stick to it
What is the fluff behing this fleet/mark anyway?
Any specific plans for that MoS? Or just the general downgrade to the enemies leadership?