I thought I'd pop in here, given that I had my first game against Demiurg at the Baltimore Epic Tournament (aka Games Day, apparently there were some 40K/Fantasy players there too...). I can give you some feedback on a first-time experience playing the list.
Overall, it seemed a nice list to play against. There were definately weaknesses. Some very powerful units - durable, offensive and extremely fast AA, terminators on bikes ÂÂ

- but they didn't seem too powerful. In fact, with hindsight, I think I drastically overreacted to the bike-terminators, landing an unreasonable number of angry Grey Knights on them far too early in the game. The strategy rating of 3 seems a little odd - I would have said a low SR would be more in-keeping with the "alien dwarf" feel.
I have only two complaints:
Stubborn.I really don't like the mechanic, if this is in any way possible to change. It's really not very fun to fight tooth and nail to score points in combat, roll dice and then have you reroll a duff roll. It also doesn't sit well with me - yeah, you're stubborn. That's like Fearless, only not quite, right? Your guys just don't give up or run away. So explain to me why this means that you're more likely to win combat when I'm killing your guys? Fearless means your guys don't die when I kick your arse. Stubborn means that MY guys die when I kick your arse. What?
Statistically speaking, it's extremely powerful, and it can really swing combats. Let's say I win combat by 1 and I roll a 4 as my highest roll. You score a 1 and a 2. You reroll and get a 6. You go from losing by 3 to winning by 1. Thats a really BIG DIFFERENCE! That's not "your guys are pretty stubborn and won't run away even if we kill them" so much as "your guys are on super magic juice"...
The probability of rolling a 5 or a 6 on either of two dice is 0.55 (i.e. a decent assault resolution roll). Now, add in the re-roll, the probability goes to 0.68. Over 10% increase, not only that but the probability of rolling a 1 or 2 (i.e. a really bad assault roll) goes from 0.11 to 0.05. That's a fairly significant boost, FAR more powerful than assuming each formation has a free inspiring character.
So I don't like it. It's frustrating - your heart leaps when you see that "1" before you remember, it really isn't a Fearlessish analogue as it impacts the outcome of the assault not whether you run away. It also doens't protect you from suffering extra hits or being broken from shooting.
Alternative possibilities:
1) Stubborn provides a save against hackdown hits
2) Stubborn allows a formation that loses combat to take the hits yet fight another round of combat instead of withdrawing
3) Stubborn provides some kind of TSKNF type resilience against BM
Deflector shieldsThe second thing I didn't like was your strange deflector shield thingies. I dislike anything that just cancels out a special rule (yeah, I don't like living metal either, was a stupid idea in 40K in the first place). The idea of a forcefield that stops macro weapons or titan killers but has no effect on small arms seems odd. The net result is that the sorts of weapons I bring along to twat war engines are unsuitable so these mighty war engines are going to get attacked by guys with swords and pistols. I guess it isn't unbalanced per se, but it seems odd. The other thing was these fields apparently work in close combat, yet most force fields don't as troops can enter the field. I thought the old squat vehicles just had Voids? Was there some reason they couldn't just have Voids?
But overall I had a terrific game and the list seemed largely fine to me, so ÂÂ

from me - it's easier to write about what I didn't like than what I did, so my enthusiasm for Xenos has been somewhat boosted.