" The only major imbalance that i recall offhand is the potential gain of players in the thief guild in the S category, and that imbalance has been corrected (?) from what i understand."

For combat, the low end (non-haste guilds) is at maybe 1.5 million per hour. High end would be fighters and paladins who can get upwards of 10 million... And all otehr guilds in between at different ranges.

S and M are the same as far as this is concerned. The low end is at 1 million or so (tinker, fighter), the high end not counting thieves is over 2 million... 2.3-2.5 (necromancers, AMs, CLs). With all other guilds being someplace inbetween (enchanters at about 1.35 million, Paladins 1.7 or so).

"Personally, i was happy to see the xp buffers go, even though my main character derived zero benefit from the removal (was already beyond their affect, being of high level already)."

If the buffers went back in, with a static 1 million/hour, it would affect your main character and well, every character. This is a change that would quite require a pwipe.