Let me chime in with a difference perspective as a player who reached fame V with 1 character and now kind of wish I didn't. I also had other characters at 99% and 98% before reset.
First, the advantage is really not that big at all considering myself, and probably most other players, don't have full sets of 5 star soul stones on our characters, meaning all that my fame 5 character gets is one extra 3 star soul stone. And it will be aeons of time before I have a full set of 5 star soulstones, so this will not change.
The disadvantage out weighs then the advantage in my opinion, here is why - from the Admin in a reply above:
You can think it as that they received a bonus for getting to the previous requirement earlier, but they will still have to make-up exp difference once tier VI is added.
So basically what that is stating is that my fame 5 character is going to miss out on a lot of experience gain, probably a good months worth of play time, depending on
a: when fame 6 comes out and
b: how long it takes for our other characters to reach fame 5.
That is a lot of hours of play time / exp that my character will be missing out on for relatively small benefit of having only one more 3 star soul stone.
So it's give and take, I'm not upset either way because as I stated the advantage works both ways and the loss is really not that big, just pointing out that fact.