Im not too sure, dont have my codex on hand, but i think a falcon would prevail over a fire prisim in this strategy. I think the focused has a smal blast, but if it does, if the player is smart you wont nab many more SMs like that and the dispersed is too weak to peirce their armor. Get a falcon if possible and load up a starcannon. 4 ap2 weapons all wounding at 2+, 2 of which insta-kill multi-wound SMs. but yeah.
Anyhow the list
Its decently fast with a ton of wave serpants but if your enemy is like mine with a squad or two of marines that are only too happy to brave ap3 (or in this case ap1) to get up close and personal then your army is in BIG trouble. Against SM armies i would favor howling banshees, you can get rid of the SMs annoying shooting and beat them down with those power weapons. A good mix of banshees and fire dragons instead of gung-ho FD would give this list a big boost, and rangers might help too instead of dire avengers, just to annoy them and that occasional AP1 shot. (upgrade to pathfinders and that will be a 1/3 chance)
Anyhow the list
Its decently fast with a ton of wave serpants but if your enemy is like mine with a squad or two of marines that are only too happy to brave ap3 (or in this case ap1) to get up close and personal then your army is in BIG trouble. Against SM armies i would favor howling banshees, you can get rid of the SMs annoying shooting and beat them down with those power weapons. A good mix of banshees and fire dragons instead of gung-ho FD would give this list a big boost, and rangers might help too instead of dire avengers, just to annoy them and that occasional AP1 shot. (upgrade to pathfinders and that will be a 1/3 chance)