My only problem is with this list is that the Coven does not do much for infantry. Most importantly, they don't help our low-MAT infantry hit. You are going to want some infantry to block lanes and such (Knights are great for this, esp. with Occultation), but your jacks, with Infernal Machine, are going to be doing your heavy lifting. My list would cut much of the infantry:
Coven +5
DJ -12
Nightmare -10
Ripjaw -5
Deathripper -4
Bane Knights (full) -10
Bane Thralls (min) -5
Bane Thrall UA -3
Tartarus -4
Siren - 2
This hangs on to your Bane Thralls, essentially trading in the Satyxis and Nyss Hunters for Bane Knights and a Nightmare. The girls just have so much more to offer your jacks, it would be a shame not to take advantage.