From the preview:
"There are some balancing issues in the beta and most of these come from the newly added weapons as well as the Stockpile gametype. The Focus Rifle and Plasma Launcher, the Covenant equivalents of the sniper rifle and rocket launcher, do seem a little too powerful. Even the rocket launcher seems to have some added splash damage that to a Halo 3 veteran seems too strong; but maybe that’s how strong they should be, seeing as the rockets were a little underpowered in Halo 3. This is a beta after all and the point of it is to find out what is good and what is bad, so expect to see things toned down or even up in Septembers release."