Looked at the stats for impalers in 43k and decided to compare the Impaler Carbine to a Plasma Gun.
Impaler Carbine|Plasma Gun
Range: 100|90
RoF: S/2/4|S/2/-
Damage: 2d10+5 Impact|1d10+7 Energy
Penetration: 6|6
Clip: 60|40
Reload: 1 full action|5 full actions
Special: Tearing|Maximal, Overheats
Weight: 9 kg|18 kg
Availability: Scarce|Very Rare
Longer range, full auto capability, -1 minimum damage but +8 maximum damage, bigger clip, five times faster reload, doesn't overheat, half the weight, and two levels of availability cheaper. Impaler carbines in 43k are overpowered.