Hi!
Still on Debian Sid at the moment, but look at this:
martin@merkaba:~> dpkg -l | grep systemd             
martin@merkaba:~#1>
Guess what?
It simply works.
Network Manager, suspend, external drives… only thing was that 
Pulseaudio was not started with Plasma session startup. Manually 
starting it worked nicely. Also the boot up was very quick. I saw some 
failure during boot quickly,  but it all appears to be working. I 
installed bootlogd to have a closer look next time.
I already thanked on debian-init-diversity for the awesome work.
I test this setup for a little longer, report bugs, if any to Debian and 
then I may add a new challenge to it. Switch to runit and/or Devuan.
I bet I may switch to runit first, but then eventually I switch to 
Devuan. Cause I like to help testing the awesome work of KAction and 
Mark for Debian init diversity, before switching to Devuan.
I bet switching to Devuan would not be any issue anyway, after this 
worked almost without a glitch. The only thing that comes to mind would 
be systemd-udevd => eudev.
I bet Debian and Devuan are much closer than years before.
Exciting times.
Thanks,
-- 
Martin