A walking Tyrant with a Guard or two and Old Adversary surrounded by shooty units like Hive Guard and Deathspitter Warriors makes for a good amount of improvement on shooting, especially if anyone is stupid enough to try and charge you (Overwatch can work both ways, baby!).
Speaking of Overwatch, and I'm sure this has been mentioned, but if you can charge an enemy unit with an expendable unit first, and they make it into combat, the enemy can't fire Overwatch at any other units, so you are then free to charge your more powerful units into combat risk free.
As I was looking over the doctrines of psychic powers, I noticed a couple of neat powers in there. The Swarmlord potentially can get a lot of really awesome powers, especially when you consider that he gets to generate 4 powers. That gives you a good number of chances to get the powers you really want. Iron Arm, anyone? It would make your Swarmlord far more difficult to kill, especially against things like Force Weapons. How about Endurance? You'd give Tervigons a self-esteem problem with that one. Twice the range of Catalyst, plus It will not Die? Holy crap, with all of our multi-wound model units and the new rules for wound allocation, you could be regaining a ton of wounds, especially if you have been shuffling your models around. Telekine Dome could be a useful ability, since you could use both it and Endurance to get more of your units beefed up. LOL, how about Gate of Infinity? Perhaps not the most effective ability, but boy would that be scary to face (Surprise! Swarmlord in your face!). Objuration Mechanicum could easily fry vehicles, and forcing the re-rolls on 6's is nasty. Finally, Invisibility. Sure, it takes up both your warp charges, but giving a full unit of Raveners +3 cover and making enemies hit them on 5's in CC would be lots of fun.
Though it is only a 1 in 6 chance, if the Doom got Iron Arm and a good roll... muahahah...
To clarify on shuffling, basically, keep a couple models in the front of the unit, as soon as they start taking wounds, move unwounded models up to the front of the unit. Now those models are taking the wounds, keeping more models alive until you can charge. Also, don't forget that you only have to continue allocating wounds to a single model until the wound pool is empty.