it is six of one half a dozen of the other, scout bees looking for a new home for a swarm may communicate to the masses this is a potential new home. the nature of bees dictate that all the scouts visit potential home sites until they all agree on the best one. and you may catch a swarm! Robbers however will clean the hive out leaving empty comb for the new bees to dress up and use. As to weather or not they will return is anyone's guess, by the time your bees get to you there will be a lot in bloom, in fact you should be on the brink of a flow, It is unlikely the robber bees would choose to do battle over stores when there are easy pickings everywhere. by the time a dearth comes along your hive will be strong. you can close the hive up and preserve the bootie for your bees, which will diminish your chances of catching a swarm, or leave it open. if you choose the later I would however keep an eye out on the package for a while to be sure they do not have a robber problem.