I used energy transfer, stealth enhance, and retriever. This setup is beast because the shotgun is 1 shot kill even in armor mode. The shotgun only has a 5m range on it but works well with Grendel. Since the Grendel is best at medium to long range shooting, the light shotgun attachment really makes this gun versatile.
http://www.youtube.com/watch?v=k5xmNsXQpl0&feature=channel_video_title
That's a link to one of my games with it
I'm not so good at commentary but decent game play.