The guild change only really benefitted 1 guild, the core group of THC who where the ones pushing for it.
It was this same core group that turned up for bosses/pk, they only recruited more people in order to try take SW. Once they couldnt do this they cried for their own buff and "adapted" by kicking the people that were not part of their core group anyway.
Any of the other guilds who had more than 30 members, remember not everyone in a guild is on at the same time all the time (unlike THC's core) have since lost people to form 10-20man guilds for the extra exp/drop buffs. These people are no longer able to partake in any bosses, due to THC's core member group already being higher level and better kitted than them anyway so can easily wipe them from bosses.
The only way to compete with people higher level and/or better kitted is to try out number them, but THC/Jamie has done a good job in nerfing that by forcing people to go into smaller guilds in order to try and compete with the extra buffs.
For the self proclaimed "pvp" guild, THC have done a good job of removing any competition. At least previously there was always a fight, some THC would win some they would lose. Most of the time it would be 1-2 SD groups vs the THC core group, rarely this 40v10 **** that keeps getting spouted about.
The only time SD manages to get most of its members together is actually for SW wars, and as people can see when checking back over those results, actual SD members at wars is around 40-50 (less if you remove the chinese players who joined to help).
While we have 80-90 members a lot of them are casuals. We start kicking those from the guild to gain the buffs and they will stop playing all together.