My first Ordo Malleus army

This is my first 40K army since Rogue Trader, so of course I'm looking for all the comments I can get. Be adviced that the army is primarily based on having a high coolness factor e.g. power armored grey knights are ruled out, so it won't look like just another space marine chapter, and I have a weak spot for assassins, so they're in.

Inquisitor (Elite) 68
Psycannon + Auspex + Artificer Armor + Targeter

Vindicare Assassin 110 - he's been standing on my desk for 10 years, just waiting to see some action

3 Death Cult Assassins 120

1 x GK Grand Master 183
Psychic Hood + Mastercraft NFW + Auspex + Targeter
w.
5 x GK Terminators 245
Incinerator

2 x 6 Stormtroopers @ 88
2 Melta + Rhino + Smoke Launchers + Extra Armor

1 GK Dreadnought 154
Twin Lascannon + Incinerator + Searchlights + Extra Armor + Smoke Launchers

1 GK Dreadnought 149
Twin Lascannon + Missile Launcher + Searchlights + Extra Armor + Smoke Launchers

GK Redeemer Land Raider 295
Extra Armor + Storm Bolter

I'm considering demoting the grand master to a brother captain and shave a few points here and there, in order to throw in another 3 Death Cult assassins. What do you guys think?

Looks good though I'd try to beef up your IST squad numbers and/or add another instead of trying for more DCA's. I'd also give your Inquistor Termie armor and run him witht the GKT's so he'll be able to move and shoot with them. He won't last long solo or with the small IST squads you have. Just to let you know that a model in Termie cannot take targeters. Will all your opponents allow you to use Forge World rules so you you can field the Redeemer?

if your inquisitor is here only to enter the vindicare, you can save the points of the psycannon. An inquisitor without retinue (mystics, heavy bolters or melta) is nearly useless except to enter an assassin.
death cult assassins are very fragile (poor savings) and expensive, you could forget it, in my opinion, except if you love the minis so play them
for the GM forget the psychic hood if you mostly play against deamons : deamons powers are NOT psychic ones and buy him a psycannon much more useful.
the stormbolter of the redeemer isn't very useful, keep your points and use them elsewhere.
my last advice : keep your GM, the BC is cheaper but more fragile (he's the only HQ heroe with 1wound and not 2), and the GM have the ultimate NFW which is very powerful against deamons.
Aubec

Aubec is right about the stormbolter on the redeemer. You want that one to be zoooming 12" every turn towards the enemy and burn something, so it will only be able to fire one weapon each turn. Which would be the assault cannon/psycannon? dno if its the FW one.

Its a really small list though!

The Inquisitor would probably love to run with termies - but the Redeemer (yes it is the FW one, and I wouldn't expect any problems) only fits 6 terminators, so I planned for him to hitch a ride with a unit of ISTs - was wondering whether I should downgrade him, and just run with a bolter - seems a little off for an inquisitor to be kitted for war - thats what the troops are for.

I'll go with the assassins at first. They do make the army look the part - perhaps later I'll exchange them for more ISTs/GKs. Also my wallet will prefer taking baby steps here, since I'm going with DKoK grenadiers - so its almost 50£ a unit + rhino

your inquisitor : may be with a little psychic power like (don't know what's its name in english) : the one with 1D6 assault shooting strength 5 ... so for sheap price he will be effective in shooting phase.
Aubec