Not really a very informative post, but I thought you’d be interested into the following:
I moved most of my computers to systemd. On most of them, the boot process is tremendously faster. I haven’t noticed any problem (with somehow heterogenous hardware – but all i686/IA64/AMD64 though). Plus logs got more relevant messages. Have a try!
Also, I finally understood what KDE activities are for. It’s, contrarily to what I assumed beforehand, not a bigger subset of virtual desktops. It’s some kind of mini-session instead. For instance, each morning, I usually browse 5 or 6 news websites. Before KDE activies, either I typed their URL in my Konqueror page or I used bookmarks. I only created an activity “News” with a Konqueror open on each news website. And, now, I just fire and shut down this activity whenever I want to read news and that’s it: it’s fast to start and shut down and it saves me lot of clicks or keystrokes. Other example? I also created an activity to watch vidéos. I fire it up and, tada!, I get plasmoids that give me direct access to the relevant directories where I store such files. Really neat. It’s fast. It just lack a bit of polishing/KDE integration. But I’m sure that a work in progress.