About a year or so ago, and after several, multiple, repeated, recurrent problems with akonadi, I decided to drop the whole kontact thing and switched to chromium and google's resources.
I have been giving it another shot these last days and (with akonadi-google) I am impressed. I have only had minor problems

Anyway, the question is:
given that it is not easy to setup akonadi and customize contact to my liking (notes, contacts, calendars, kmail, etc),
how confident can one be that it is not going to be in vain?
i.e.
can we be confident that there won't be a complete makeover in akonadi or kontact that will force the user to set everything up anew?
Additionally,
how portable are akonadi and kontact between distros?

thanks and thanks to the developers for akonadi and kontact!

As far as I am aware, Akonadi based setups are going to continue to be the norm for the remainder of the KDE 4.x series at least. At this time, no plans exist for the KDE 5.x series, however I would not expect significant changes to occur there.

Current work on Akonadi and the application counterparts involves polishing, bug fixes, performance improvements and new features (including the return of temporarily lost features as part of the Akonadi port as well as completely new features).

That's exactly what I wanted to hear!!! (I just hope you are right! )
Do you know anything about the other issue:
can I move to another distro, take with me all the akonadi and kontact configuration files and be ready to go?

I agree -- provisionally. Minor glitches in Kontact, e.g. it doesn't remember changes of address book name or icon, but it does sync the contacts between Google & Kontact. So, I'm happy. Kind of.