Can’t properly test but the health bonus seems to be absolutely obscene.
As WHC on champion using the crossbow a headshot Crit followed up by headshot is insufficient to kill a single life leech.
As IB a trollhammer shot cannot kill a gun rat with a direct impact on champion.
On recruit it takes 2, sometimes 3 attacks, to kill a critter rat.
A slave rat will not die to a critical headshot from a crossbow on WHC on recruit.
Based on endgame damage it would look like around 15x the HP is the actual modifier instead of 2.25x.
The extent of my testing so far: a single chaos fanatic (smallest infantry) has over 28 health on recruit. Factoring in the reduced power level makes these small units incredibly difficult to kill.
Clan rat has 30 hp on recruit.