So I came across this because I literally had the exact same idea, and even some of the exact same ideas you had. Some of my suggestions are though, instead of Daemonette Swords, I figured that the Emperors Children could be using some sort of pain amplification weaponry, similar to Fabius Bile's, or even just injecting people full of daemonic ichor to represent the instant death effect.
I called Aegis "Psychic Resonance" instead, representing the interference that the constant sonic weaponry waves could be causing. Warp Quake would just be "These go to eleven" cranking up the resonance even higher to cause major disruption in targeting equipment and teleporting.
For Hammerhand, I was saying it was a drug effect, like PCP, and Perils was an overdose.
I like your "Amplify" idea for the purgation squads, as well as the Chosen as your Purifiers.
For Dreadknights I was going to make Hellknights: http://4.bp.blogspot.com/_gKXe619YS5...ellKnights.jpg
I think for weaponry we had the same ideas, sonic blaster = storm bolter, blastmaster = psycannon, doomsiren = incinerator. Instead of Warpbolt ammunition, i was going to give them "Amplifiers" which are represented by speakers built into the armor and/or backpack.
Great Inspiration though! I'm glad that I'm not the only one to see how well the rules actually fit.