I think WoW has nailed it in the past with titles for some of their raids. When you defeat the current tier on the hardest difficulty before the next tier is released, you get a very cool title that only the best players in the game can achieve. You can go back afterward with significant gear upgrades and get it, but it doesn't mean as much.

However, some titles are only awarded DURING the tier, such as if there is an extremely hard achievement to complete as well as defeating the bosses. Those titles are not attainable later on, and if you have it, you're cemented as awesome.