Why is there still an argument going on? The people against the split are saying, "I don't see the need, but I guess we could try out a few sublists, if for nothing else then to keep you idiots quiet." The people who want the split are saying, "You reactionary running-dog bastards, I demand that we try out a few sublists now!"
So, what exactly is all the shouting about? Let me summarize what everyone on all sides seems to be saying minus the rhetoric, and see if there's still any substantive disagreement: Step 1: Create a few sublists. Accept that this may not be the final breakdown, but a good starting point is Warly's suggestion (install tools, config tools, and GUI) plus Buchan's server-specific list. Step 2: For now, forward all of the lists to the master list cooker (munging reply-to if necessary), so people who don't do anything will continue to see everything. Alternatively, provide an easy way to subscribe to all lists at once (a message sent to everyone on the list that, if replied to, will subscribe you to the other lists). Step 3: Leave bugzilla alone, and everything else. Step 4: See how it goes.
