Updated my Soundpack using some ideas from
this thread and
Bundy's. (Replace the old one, please.) While its size is more than 4MB now, I'm not gonna send it to your mail, because of Web.de's attachment limitation.
I had some samples in my mind for this possible ranking system of yours. Depending on what the player is doing, he gets a different message.
Flag Carrier Backup/Assisting - frags made from a certain area next to your carrier:
3 frags - "Assist"
5 frags - "Protector"
10 frags - "Hero"
Flag Capturing:
3 flags - "Hattrick"
7 flags - "Ninja"
(missing another ranking

)
Base Defending - Frags made in a certain area next to your flag:
5 frags - "Cleaner"
10 frags - "Guardian"
15 frags - "Samurai"
Also if you get the guy with your flag AND return it, you get a "Safe".
These are only concepts. I could record any other sounds of course.
But I like the general idea of this rewarding system. In ET I was usually playing just to get the "Best Medic" award

Of course, you can't do such a thing in Nex, but maybe these rankings could help to make people play as a team.