Parallels and "new" versions of Windows and Ubuntu

I though it would be a good time to upgrade my existing OS's under Parallels 10 and once I've done that probably switch to PD11 or even PD12, even though Parallels is the software I usually upgrade at the last possible time because of the poor support and maturity.
STATUS: PD 10 latest upgrade and Windows 7 and Ubuntu 14.04, working like a charm...
EXPERIENCES:
Windows
Installed Windows 10, even with all the tips from the forum (had the 100% CPU usage problem, reinstalled PD etc.) Win 10 still needs about 2-3 mins to boot - compared to the approx. 35 secs of my Win 7 installation that I use for years now with all kinds of software installed !!
So, Windows 10 with Parallels: not an option for me.
Ubuntu
Upgraded Ubuntu 14.04 LTS to 16.04 LTS and ended in an unusable installation (login loop, tried all the tips, .Xauthority, reinstall nvidia drivers, etc.), can only be used in text mode now...login loop. Parallels Tools cannot be installed due to Linux header props, as usual with Parallels...
Installed fresh 16.04 LTS
Installation works fine but same problems: login loop, only text mode, no Parallels Tools...
CONCLUSIO
No reason at all to consider an upgrade because I've lost trust in Parallels and upgrades are a nightmare with them. I'll investigate VM or similar and use the old version until then.
Too bad, really started good
Cheers,
N