Falcons are fine, They are rock hard scoring units. And you have them kitted out perfectly. They should do just fine for you.
If you are intent on running falcons, it might be in your best interest to run Eldrad instead of a regular Farseer. The reason being is that he can cast 2 guides a turn, which significantly helps deal with the falcon's low ballistic skill. His other abilities also all have their uses.
Vypers, they are a decent unit, however you've got them kitted out all wrong. Each one only has a single shot with bs3. Generally you want to give them scatter lasers so they can make up with their lack luster shooting with volume of fire. Consider- a Vyper with a scatter laser and underslung shuri cannon costs 5 points less than a Bright Lance vyper, and and can shoot up to 7 s6 shots. This gives them better consistancy and better damage against infantry and light armor. There is no shame in spamming s6 guns.
Eiluj is right about the storm guardians, they have no business carying fusion guns. Once again, they have a low ballistic skill to work with. At the end of the day you are paying 92 points for 2
bs 3 melta guns, when you could be paying 80 points for 5
bs 4 melta guns. The fact that storm guardians are scoring does not make up for this. Stick with flamers- you don't have to roll to hit

. The only time you'd want to consider fusion storm guardians is if your elites are already full of things you aren't willing to part with. Also, grab the warlock for them, the heavy flamer is worth the 35 poitnts- and you never know when you need to do a charge to sink that witch blade into some delicious armour.
I do agree with Eiluj that Banshees are currently better than Scorpions after the advent of Grey Knights, Blood Angels, and Dark Eldar- however the green dudes are still ok. Outflanking is cool, but very unreliable especially without an Autarch. I actually think that Scorpions work best in a foot list. In a foot list scorpions threat of outflank may trick your opponent into deploying in the middle of the board- right where your wall of Avatar and Wraithlords will be marching up. In a mech list they don't really provide anything that Dire Avengers blade storming or Storm Guardians torching wouldn't do better. That said, you do have them set up in one of their stronger configurations, and backed up by a pheonix lord they should be able to cause some carnage. Just be very wary of squads with a lot of power weapons, as poor Karandras doesn't even have an invulnerable save.