Hell yeah, trophy kills! Loved them in AVP2010, really glad to see something similar here.
The customisation and sheer number of of Jason's kills in Friday the 13th was a really cool part of that game, so hopefully we'll get a similar sort of thing here with the amount and choices (within class/weapon type at least).
And yeah no surprise about the lack of recording people's actual voices. They could still implement the same feature though, just have it be that the human characters call things out like "need ammo!", "need healing!" "enemy spotted over there!" etc. and have the Predator copy those instead. It could work well with the ping system and could catch certain less aware players by surprise if an icon and sound popped up for a teammate in need of being healed only for there to be no human teammates in the area.