Forget about ooRP grudge matches, they were mostly good for a laugh on skype and limited to a few oddballs. My experience of Kusari might be somewhat outdated, but the peculiar thing about Kusari was that most of the activity came from the official factions - which isn't the case in most other houses.
And that probably has something to do with some people being intimidated about Kusarian roleplay, thinking you need some excessive knowledge of Japanese to even begin playing there. And I choose to blame the "Kawaii, Desu Desu~" fanboy brigade for that, bombarding people with random japanese expressions and confusing them to no end. And I'm not sure any amount of storyline progression can undo that damage, especially as the glory days of my 3 year stay in ]bd[ were probably deep in 4.85, even though .86 was supposed to make Kusari more lucrative to traders, etc etc.