One thing to keep in mind with the Hunter though, is that if you want them to use sneak attack and sniper rifles, the base rules for sneak attack specify that such added damage can only be done within 30ft. Which gives me really funny sniper images of someone in the bush 30ft away and zoming in on their target's nose hairs. One other thing about the hunter. As unique as the momentum ability is, and kudos for that, I see this as becoming a logistics pain for the DM to run battles where the turn order keeps changing. Not a huge issue, but just a thought. I would cross reference this class with ranger and compare the amount of abilites each gets, because you've given it a number of abilties which become very useful in limited circumstances. Although I will admit that death attack is the exception to this, that's a very powerful ability to hand out in a base class.

So based off of the name, does this predator ability have anything to do with stalking a target, or do you not know yet what you intend to do with it?

Is this empathy implied with being an arbieter or is it a feat? I didn't know about it because it wasn't in the material you had mentioned.

And I must say... now that you've given me an image of what reaver looks like (something like the ass-kicking incarnation of River), I'm very interested in how that turns out. Is this psi blade supposed to be the exact equivalent of the soulknife or it is another one of those psionicly reactive technologies you mentioned previously.