Well, if there was a way you could click and choose which topics could come or stay, it would be great, but IIRC I don't think you can do that.
IMO we've already started, and we have a foundation again, so let's keep this one. However, i would kinda like to see the old version up, for any posts or things I missed
Yeah, just have S.net v3.0 as a read-only archive somewhere else on the site and keep v4.0 as we have right now.