Well against the zerg stasis isnt that good against the swarm as they have many unit. Using stasis on a few wont help that much unless blocking a choke. But then again zerg often attack at several location. When protoss attack the recall might help but in most case a shuttle or 2 would be enought. So against the Swarm i dont think arbitrer is good considering the tech level and the ammount of gas required. Not to mention the build time. I would prefer much more having more ht.