I think they really, really need to lose eternal warrior. Or at least the two wound models, then. (screamers and flamers, it's fine on blood crushers) If nothing else (and there's a lot else) it get's you to thinking, "So....why do daemonhunters have force weapons, then?"
Fearless....meh, they're non-human, but someone pointed out to me than daemons should actually probably be hyper-emotional, so fearless doesn't really make sense. I dunno.
I'm pretty sure I don't really want to see anything like the old instability (for 40k, for fantasy I think it's fine), mostly because it seems to me nearly impossible to balance. I.e, a demon unit will either be just murdering whatever else it is, or will lose badly and just get wiped out, with very little in-between.