Well, the title, keyword "Title" you receive for obtaining all the pieces of gear for the event is for those who have taken the time to reach level 60 on all their jobs.

However, you only need to level 1 job to 60 to work towards obtaining the 3 mounts as long as you are using the title you received from that 1 job. So with that in mind, there is no reason to change the gear to lv 30 since the title reward is an achievement for those who have gotten the jobs at 60 and are capable of wearing the set for each job.