Quick summary is that the site got really, really slow and then eventually crashed. Mel set up DW to use when Hitched was down but, even when it was back up, people were still having problems and found posting on DW easier especially from iPhones.
Then there was a bit of a hoo ha on OT with Darren telling people off for swearing. People on OT were pissed off because he had done nothing to fix the problems but then came on telling them off so decided to migrate to DW.
BT pretty much stayed here for quite a while until a few big names moved over and then slowly more and more went. BT here went through a very quiet phase but has definitely been picking up recently.
Apologies for lack of capital letters - Zoe has stolen my shift key 