Here we go.
I made my decision. Like I mentioned, the new Kubuntu 15.04 is out and I'm going to switch from Manjaro 0.8.12.
I very much liked Manjaro, and this is a hard decision. But I really like the new features and look of the "evil" Kubuntu and the stable updates.
Maybe I'll come back to Manjaro, one of the best GNU+Linux distributions I've ever used.
Loads of green tea are ready, backups are made, and now I'm starting first the update of the Windows 8 partition (Battlefield only, no backup necessary) to 8.1 which apparently overwrites the mbr. Then I'm installing Kubuntu which hopefully will work with my harddisk setup.
Go go go. Ganbatte!
Edit 11:10: I should have knew it. Windows 8.1 update fails. Can't proceed. Tried clean boot and everything with no luck. Screw Microsoft! Forgetting about Win 8.1 for now. Proceeding with Kubuntu 15.04 now.
Second Edit: Install of Kubuntu succeeded. Works great like expected. A bit unstable after installing nvidia driver, switched back to xor nouveau - stable again.
I had to install some additional software. A lot. Quick boot and what a joy, it shuts down like in a second or two. Great.