Well, it has been weeks of preparation, but I'm happy to report a successful MIGRATION
of our live server. :woohoo:
We have a really plain-jane Joomla 3.4.8 site, with very little 3rd party added but CB/CBsubs and a Kunena forum.
After much testing, we arrived at a functional "Migration Checklist" which tested good on our DEV server.
It might not be specifically applicable to your setup, but if you are still "late to the party" and haven't migrated your CB yet, you may find it useful to look over our checklist, to prep for building your own!! In our site, few features in CB are enabled (No PM, blogs, CBarticles, most profile data is hidden,etc) so our configurations for tabs and fields likely will be very different from yours. But if you read through our checklist, you will see all the things we found that we had to "tweak" to perform a seamless migration, and a few 'gotcha' workarounds specific to our configuration. Hopefully someone out there might find the attached PDF useful!
Anyway, now that we have CB/CBsubs up to speed, next up we can finally roll out that Joomla 3.6 upgrade ...