Speaking as a user, only ....
Yes, the Debian packages come only from the sid repo.
The new kernels are build by our hero, towo, and come from the siduction repo.
The grub splashes, kernel-remover, and some other packages come from the siduction repo. If you will follow a couple of simple rules, you should not have a problem with siduction:
1. Not less often than once per week:
apt update
apt full-upgrade -d
Ctrl-Alt F1, log in as root.
systemctl isolate multi-user.target
apt full-upgrade
If there is no new kernel, then
systemctl isolate graphical.target && exit
If there IS a new kernel installed, then
systemctl reboot
2. Look at the message from apt. Look for packages to be removed. If any packages are to be removed .... CAUTION!
Check this forum for Upgrade Warnings.
Sometimes we wait for a time, until the transition settles down and lets us have a safe upgrade.