Couple of notes on the wraithknight (if you haven't used him), at 1500 points he is a complete monster so long as you are aware of the few units that will take him out (usually in a suicidal manner). He hates the grav but a 5++ and 5FNP mitigate some of that but a centstar in a pod can put on more wounds than you can save; stay in cover. Practice with stomps, reread the rules. You can use them to devastating expense as long as you use good placement. You can walk them out pretty far.
As of yet Incubi have done very little for me, as have haywire scourges; at least as far as point efficiency goes. That being said, an autarch with mask is pretty sweet sauce. Give him wings to shorten charge distances (he can move 18 so its easy to get another three inches closer than the lead incubi.) You will get alot more out of scat ot canons on the windriders than you will the scourges. The wraithknight with the sword pretty much destroys Imp knights before they can hit back, so their direct need is not as great.
With scat lasers on your bikes, you can pop transports for the venoms. Hornets are not a bad option and you can get three with pulse lasers with the loss of the ravanger and razorwing. Hornets are very good. Each has 4 8/2 shots so three get 12...at 48 inches as opposed to our ravanger that gets 3 at 36 and is open toped and is av10.