9 Raveners
2x scytals
54 attacks
first hits(3+): 36 hits
reroll hits(3+): 42 hits
wound(4+): 21 wounds
Save(3+): 7 damage

rending
36 attacks
hits: 24
wound(4+): 8 + 4 rending
save(4+): 4 + 4 rending

W/Red Terror (+1 to hit rolls)
2x scytals
54 attacks
first hits(2+): 46 hits
reroll hits(2+): 52.5 hits
wound(4+): 26.25 wounds
Save(3+): 8.75 damage

rending
36 attacks
hits(2+): 30
wound(4+): 10 + 5 rending
save(4+): 5 + 5 rending

9x Devourer
27 shots
Hits(4+): 13.5 Hits
Wound(4+): 6.75 Wounds
Save(3+): 2.25 Damage

9x Deathspitter
27 shots
Hits(4+): 13.5 hits
Wounds(3+): 9 wounds
Save(4+): 4.5 damage

20 Genestealers
80 attacks
hits(3+): 53.333 hits
wounds(4+): 17.777 wounds + 8.888 rends
save(4+): 8.888 damage + 8.888 rends

w/Broodlord
80 attacks
first hits(3+): 53.333 hits
reroll hits(3+): 62.222 hits
wounds(4+): 20.741 wounds + 10.370 rends
save(4+): 10.370 damage + 10.370 rends

30 Hormagaunts
60 attacks
first hits(4+): 30 hits
reroll hits(4+): 35 hits
first wounds(5+): 11.666 wounds
reroll wounds(5+): 13.61111
save(3+): 4.537 wounds

Close Combat
Weird thing here was that in point efficiency, despite more wounds, the rending claws were less point efficient than the 2x scytals.
9 warriors
2x scytals
45 attacks
First hits(3+): 30 hits
reroll hits(3+): 35 hits
wounds(4+): 17.5 wounds
save(3+): 5.833 damage

rending
27 attacks
Hits(3+): 18 hits
Wounds(4+): 6 wounds + 3 rends
Save(4+): 3 damage + 3 rends

Boneswords(-2 ap)
36 attacks
hits(3+): 24 hits
wounds(4+): 12 wounds
save(5+): 8 damage

Shooting(4+)
9x Devourer(Assault 3,4S,-AP)
27 shots
Hits(4+): 13.5 Hits
Wound(4+): 6.75 Wounds
Save(3+): 2.25 Damage

3x Venom Cannon(Assault d3, 8S,-1AP) + 6x Devourer
D:18 Shots
D Hits(4+): 9 hits
D Wounds(4+): 4.5 wounds
D Save(3+): 1.5 damage
V:3d3 shots(6 ave) vs T8, 3+ vehicle
V Hits(4+): 3 hits
V Wounds(4+): 1.5 wounds
V Save(4+): .75 damage

9x Deathspitter(Assault 3, 5S,-1AP)
27 shots
Hits(4+): 13.5 hits
Wounds(3+): 9 wounds
Save(4+): 4.5 damage

3xVenom Cannon + 6x Deathspitter
D:18 Shots
D Hits(4+): 9 hits
D Wounds(3+): 6 wounds
D Save(4+): 3 damage
V:3d3 shots(6 ave) vs T8, 3+ vehicle
V Hits(4+): 3 hits
V Wounds(4+): 1.5 wounds
V Save(4+): .75 damage

Because of the bonus to hit the rending claws did pass the 2x scytals for point efficiency here.
Close Combat
2x scytals
45 attacks
First Hits(2+): 37.5 hits
Second Hits(2+): 43.75 hits
Wounds(4+): 18.75 wounds
Save(3+): 6.25 damage

rending
27 attacks
hits(2+): 22.5 hits
Wounds(4+): 7.5 wounds + 3.75 rends
Save(4+): 3.75 damage + 3.75 rends

Boneswords
36 attacks
hits(2+): 30 hits
wounds(4+): 15 wounds
save(5+): 10 wounds

Shooting(3+)
9x Devourer(Assault 3,4S,-AP)
27 shots
Hits(3+): 18 hits
Wounds(4+): 9 wounds
Save(3+): 3 damage

3x Venom Cannon(Assault d3, 8S,-1AP) + 6x Devourer
D:18 Shots
D Hits(3+): 12 hits
D Wounds(4+): 6 wounds
D Save(3+): 2 wounds
V:3d3 shots(6 ave) vs T8, 3+ vehicle
V Hits(3+): 4 hits
V Wounds(4+): 2 wounds
V Save(4+): 1 wound

9x Deathspitter(Assault 3, 5S,-1AP)
27 shots
Hits(3+): 18 hits
Wounds(3+): 12 wounds
Save(4+): 6 damage

3xVenom Cannon + 6x Deathspitter
D:18 Shots
D Hits(3+): 12 hits
D Wounds(3+): 8 wounds
D Save(4+): 4 wounds
V:3d3 shots(6 ave) vs T8, 3+ vehicle
V Hits(3+): 4 hits
V Wounds(4+): 2 wounds
V Save(4+): 1 wound