What does the blasterborn give you that a Ravager wouldnt? (other than another venom) which can be mitigated with a better useage of your points into troops. How about this:
50- Haemie
95- 3 Wracks in venom w/ dual splinter cannons
125- 5 Warriors w/ blaster in venom w/ dual splinter cannon
125- 5 Wyches w/ Haywires in venom w/ dual splinter cannon
105- Ravager
500pts exactly
Same amount of darklight shots that you had, but 3 are now 36" range instead of 18. To top it off you still have haywires from the wyches to deal with things, and more AI through 3 venoms.
Also if you dont like the composition of the list in troop slots, all 3 of our major troop slots are the same points cost (5 warriors w/ blaster in dual cannon venom, 5 wyches w/ haywire in dual cannon venom, 5 wracks w/ liquifier w/ dual cannon venom) so the list is very modular to your tastes (personally I wouldnt run the wyches, and would run another warrior squad instead)