Having a lot of fun with this build. I decided to put the lasers on the torsos instead of the arms as the Phract's arms are too low for my taste (in fact the arm UAC is a bit of a problem because of this). That also allows you to remove some armor from the unused arm. IME most of the time you can compensate for the lack of arm mobility by jumping, especially with anything that isn't a 1s-duration laser. As usual with this kind of builds, when it gets hot limit yourself to firing the UACs. EDIT: this is the build Celyth used to win the last tournament in the IS heavy category.
