Just FYI, even with just 39 players, the gap of "group 1" of each server cluster is going to be 40-100k (that is to say, 60-70k minimal with whatever highest ptw is, which is 100k+ in most clusters, highest being 163k, which means there could be a 100k gap there)
Now, if they can get rid of clustering and put all server of a region in one pool, then group 1 would be all 80k+, thou that still means 30-80k gap.
So in the end, group 1, regardless of size, would *.
Now, if the group size changes every time, then it would be better. For example, if it changes between 30 and 75, then the player 31st to 75 c*l be "top" of their group sometimes(when the group is just small enough) whereas the 11th to 30th player have a decent change to win when the group is large as they can beat MOST of the players so they have a chance (granted, chances are 21st to 30th will almost never win, but that would require more complex change)
There is also rumor that the grouping aren't done as promised, that is to say there are, for example two 40-100k lv 90 groups(instead of say 65-100k and a 40-65k one) within the same server cluster. That said, of the fellow 90 in my group that I was able to talk to, they were all in the same sage.
Anyway, overall, Xserver sage is messed up in many ways, I'm not sure if it really can be fixed...