Being a forum user from a foreign land I don't know whether it is right or not for me to comment on this subject but a few thoughts come to mind.
As Warren mentioned, you could stick the general discussion forum at the bottom of the page and deselect it from the new posts search facility so if you didn't frequent it, you would never know it existed.
The fact that threads do go off topic could show that perhaps there is a need for a place where a bit of non tiger chat can carry on.
Perhaps an 'other marques' forum would be a good idea too?
Can we have a Tim 'The Tool man' Taylor forum for Duke too?
I have also seen a few forums where General Chat has got nasty and it can tarnish the reputation of a club but that's all down to how it is moderated in most cases.
Bear in mind that nothing is set in stone so if it turns into handbags at dawn or an embarrassment, you could always close it.
Just a few mindless ramblings.