If there are just three Storm Ravens, pack 10 or Melta/plasma into rhinos, or Raptors and Deepstrikes or chases one a turn down. Magnus "should" break one a turn. 2 Heldrakes have a possibility of breaking one on a charge. Bloodthirsters with wings...
Forgeworld appearently has a

ton of toys.... I'm sure I missed a few in the index.
Six storm Ravens sounds a bit harder to deal with, if only because ALL that shooting is in your face turn 1. Deep striking Raptors with Power Fist/Melta Gun and a Icon of Wrath sounds effective. Melta Bombs would be nice (
GW probably won't give them to us.) Only problem I have with SIX is that it's so much front loaded shooting that they'd kill 2 Heldrakes or Magnus or 10 Havocs in a rhino. Meaning that my list quickly becomes one sided to counter them leaving me a easy counter by another army.