Eric Hameleers (AlienBOB) is now actively pushing updates on his set of packages on his repository. His latest work involved set of KDE 5 updates, new baking recipe, and the Slackware Live ISOs based on latest work of liveslack 1.1.5.
One interesting point about this latest ISOs is that Cinnamon is now included in the set of ISO generated. Previously, Cinnamon was added during early testing phase, but it never got included in the next few releases and somehow it's included in the latest 1.1.5 release. It's already based on the Cinnamon update i uploaded per December 10. Since Cinnamon is in active development due to preparation of Mint 18.1, you will notice that they release many minor releases in a short time. There's already a new cinnamon commit pushed to my github/gitlab repository, but not yet packaged. I usually wait for some time before i start packaging for stable update.
Please note that Cinnamon packages were built under 14.2 stable, not current. I will try to spend some time to build Cinnamon packages under current to make sure it stays with the baseline used (slackware-current). Same thing with MATE, but i will try to build MATE 1.17 instead of MATE 1.16 which will be based on full GTK+3 stack. I have a local branch here which already track MATE 1.17 packages, but i'm still waiting for the upstream to complete creating tarballs for MATE 1.17 before i can launch the branch to github.