Buy and large the alpha. He's a really, really effective LT – albeit a very obvious one but still relatively capable himself. As for the Gangbusters, it depends – generally what load out they're taking and what you're playing against. MSV + mimetism is really great for killing other infiltrators. When I take the combi rifle I try and take advantage of this combo and bully camo tokens and alot of enemy FD troopers. When I take the KHD they tend to play a more defensive role, just due to the restrictive nature of the rangeband of the SMG. Mines and DTWs are really dangerous to these guys, their terrible PH hurts them in this aspect compared to other infiltrators. I like the Gamma too – he's certainly not my go-to HI but he's easily one of the most durable pieces in the army, and theres value in that. As for Team Sirius, I find myself taking the FO profile now. She's a good Liaison Officer in relevant missions!