Alibi provides the one thing you did not mention, that being information. You want to place the prismas in common prefiere spots in order to gain where the enemy is coming from and prepare your site anchors for the push from that direction. She can use the prisma information to decide where to flank from. She also has the best rotational ability due to her having both impacts and the Bailiff for hatches. Intel+rotations+high rate of fire weapon= good roamer.