It is an interesting looking evolution of the pack.
However you are incorrect about ATM3 support ending.
From the packs page;
"ATM3:Remix will take over as the more actively-developed and update pack. We will continue to update the normal/legacy/classic ATM3 pack with bugfixes and content, just on a slower more "end-of-life" basis at least until the majority of the community has had a chance to finish playing their worlds without feeling abandoned. "