On my server PVP guilds last anywhere from a week to a month and there are between 1 and 3 of them going at any given time.

The major problem that pvp guilds face is that they dont offer much in the way of incentive to stick around when something unpleasant happens. In a PVE guild, people have a much higher tolerance for drama as long as things are progressing. But what can a pvp guild offer its members as an incentive to stick around? Arenas dont reward any alliance larger than five people.

One handicap seems to be the PVP players. They are in general more likely to be the kind of people that cannot succeed in PVE because of immaturity issues. They are often younger than the majority of players, with a "twitchy", hostile mentality that does them well in arenas but not playing in large groups.

What about premades? Premades have always seemed to be the key to a pvp guild that would actually become prominent.... but the dirty little secret is that PVP gear is actually inferior in BGs for many classes (I and another priest ran a really successful premade all summer, both of us usually specced holy and in pve gear) so long as you have the premade structure backing you up.