For years Blizzard has claimed that there would be no chance for faction changes. They didn't use the word "never" but they did say there were no plans on doing it. Much has changed since the Blizzard/Activision Merger. Well, the time has come, and what has become of it. I honestly can't tell you if the impact has been good or bad, but there has certainly been an impact.
If I haven't mentioned before, I play Horde. The first night that transfers came out, a number of my friends and guildies swapped characters over from Alliance. Good to see an influx of variety, but much attention turned to leveling forgotten alts. I don't know anyone who has transferred from Horde to Alliance. Given a better opportunity, I'm sure there are plenty who would make the switch.
Faction changes have had an interesting effect on guild on my server. A number of raiders from the top guilds swapped factions and joined forces with the top guilds on the Alliance side. The Alliance guilds have always been front runners in progression and this move has served to make them stronger. That's excellent for them.
On the Horde-side though, we've seen some pretty severe instability. One guild has crumbled and a new guild is rising from it's ashes. It's sad to see empires fall, but it's opened the door for some folks to move up the raiding ranks. I wonder if it's had the opposite effect on the Alliance side of the deal -- if it's bumped good, but not stellar players into a lower raiding bracket.
I've also heard tales of ninja disappearances with name changes and all. For those who play both sides or favor the other, it only stands to believe that these folks took their spoils to the other side. Honestly this behavior isn't really different from server/name transferring with an extra added level of faction complexity.
As for the raiders that merged with Alliance on my server, I don't know if they were compelled to do so by a raid leader. The guild was suffering some persistent personnel issues, and it may have been a good time to regroup under new management. There were many great players left behind. Did they stay due to Horde loyalty? A general distaste for the Alliance? Were they unwilling to pay the transfer fee? I don't know.
I am curious what the effect of race changes will be. As is stands now, it would be unreasonable to ask someone to change race. It would require having someone level up a new character to optimize racial benefits. But once race changes come out I could see raid leaders compelling players to optimize their racials. If a raid leader can ask a blood elf hunter to change from beast mastery to marksman, what's to stop the leader for asking for a switch to orc?
The dust is settling. I believe that the vast majority of transfers happened shortly after they went live. Normality should be restored. In some cases, like my server, it's just a slightly different version of normal.
WoW.com offers a plethora of information on guild leadership and guild membership. Be sure to check out Scott Andrew's Weekly Column Officer's Quarters and keep an eye on the community with Mike Schramm's Guildwatch.