Actually things have come together more quickly than I anticipated, just an xterm issue to resolve and otherwise all that I use on my normal desktop is just working. I have made some more kernel config adjustments using Gentoo's list of required and recommended config options to support systemd. The good thing is that like Knoppix, we use our own booting and init that is independent of systemd, upstart, etc. So systemd is there but the /etc/init.d scripts work as before and to the user there is no real difference.
So far the startup scripts, dependency lists, prebuilt packages, and data tarballs on the server work across Wheezy, Ubuntu, and Jessie dCore x86 versions. So Jessie dCore will still be under the 5.x major release. Since I plan to stay with one directory to support both existing and new dCore's, at least as long as possible, the next major version can be when enough changes require that we start a new directory of files on the server to cleanly support newer Debian/Ubuntu releases.
Oh, and the packages in Jessie are changing daily, so when testing my advice would be to use the list file feature of importsce and make one large SCE. If you want to add more packages, re-import that SCE with the additions. Otherwise breakage can occur due to conflicting files among SCE's. The xterm issue is all that is left before I feel confident to post a dCore.gz, I aim to fix that tonight.