From my experience, Flyers are well, somehow like this:
The only flyers that are causing problems, are no1 - Helldrake, no2. Stormraven, no3. Vendetta.
All those, have mostly AV 12. Shooting down those with S7 gun, is tough, reaaly tough, and every turn they are allowed to fly, is casuing more and more ravage.
BS4 and BS5 with twin link for quad gun are well, not a big problem. Both have high change of inflicting same ammount of shots. I dont see a reason to pay more for BS5 over BS4. (I'm speaking in BS5, becouse thats the max BS you can use for twinlinked weapon)
What the real problem is, are the vehicle damage chart rolls. I loved in 5th ed eldar codex, the dragons with Tank hunter crack shot exarch. Suddenly, that S7 could reroll on damage chart, which made it TONs better. Now we don't have anything that has this juicy stuff, so to deal with those, there are few ways.
1: Fast shot BS5 eldar exarch with Icarus.2x 2+ to hit, lascans on av12, are imo better, than 4x S7.
2: Crimson Hunter. 4x BS5 s8, from which 2 are lance, and gets high chance to hit the rear (for drakes and vends, its suddenly AV 10), and vs flyers, you reroll damage chart (!)
3: VR bomber. AV 11, with 5+ inv, and two s9 lances is good. Not as good as Eldar counterpart, but well. I have specific 2k List, that contains both of them, beeing a decent Anti-Air.
4: Guide + prescience on Ravagers. Those are good. with 3 ravagers, two of which are prescienced, suddenly it's like 15 s8 shots on a flyer.
With route no2 and 3, which are flyers, there is specific problem. You want to go 2nd. And venom spam lists, don't realy like going 2nd.
Other than that, List, I like it