Good call. Yes, there will have to be a strong link, but we can't foresee particulars just yet. One potential source of action that we're pondering now is launching the new site as "invitation only" (lucky we have this Invites module in Trident already) and inviting BoonEx folk to register.

Joined login is a little tricky and potentially cumbersome, but at this stage I won't rule out some kind of bridge.