1000 Point Mechanicum Heresy Army List

So here's the army list of what I went and bulk purchased in one go! I didn't have a clue as to the total points until I got it home, and it turns out I've got a quite nice chunk in the bag already.

HQ-
Magos Dominus on Abeyant, armed with a Rad Cleanser and Volkite Serpenta.
He's the stock Magos out at the moment, and such a great model.

Troops-
Thallax Cohort, armed with two lightning guns and one photon thruster.
An easy troops choice, and didn't fancy going for the multi-melta option just yet.

10 Tech Thralls, armed with Las-Locks.
A strange choice, being very expensive in monetary terms but ridiculously cheap in points. But they look so cool!

A Castellax Class Battle-Automata, armed with Mauler Bolt Cannon.
Since it's a non-compulsary choice I only went for the one so far.

Fast Attack-
3 Vorax Battle Automata, one armed with an Irad Cleanser.
The new kids on the block!

Well that's what I've got so far and comes to the grand total of 610 points. To edge it closer to the 1k mark I'm definitely adding in...

Heavy Support-
Thanatar Class Seige-Automata.
It's an absolute beast and a very nice looking kit.

That leaves me with around 150 points left, and this is where my decisions become a little less easy. I've narrowed it down to two choices...

Another Thallax Cohort.
Pros- Easy on the wallet, and would give me a very solid troops base.
Cons- Already duplicating squads at such a low points level. Not exciting to paint another unit.

A Krios Battle Tank.
Pros- Stunning kit. The lightning cannon is a monster.
Cons- Is very expensive on a points/pound comparison to other choices.

So there we have it. If you've got an opinion about my list, and the impending choice please drop me a comment, it would be very much appreciated!