I used my completed Hierodule (pics forthcoming) in our weekly game Tuesday night. It was quite the interesting experience. For one, we had a new player come so we did a three sided game following the rules in the back of the rulebook. Secondly, I had a 700 point unit in my army.
In the end, I don't think it is overpowered. It's not something I would do every game, but it is fun once and a while. It caused a lot of damage, but in the end was brought down by TH/SS terminators and a missile launcher. I can see how people say it is overpowered as it took out a lot of stuff, but I don't think it even earned its points back. I actually lost the game.
I also took my Malanthrope. While it is not overpowered, the more I use it the more I realize its rules are all wrong. All lookers on said they were surprised that it was more nasty in CC than with psychic powers. If they do put it in the 'nid codex, I hope they fix those rules.
The three sided game rules are interesting. I think I'd give them another try, with a bit of adaptation. For one, make sure the home bases are equidistant. If one is too far away, the other two players will weaken each other and the third can mop up. But such is the nature of cutthroat.
Anyway, I'm going to be coming up with some new scenarios for 40k. I am working on a Halloween themed one right now. I'll post it after I get it out of the rough draft phase.