Re: Best strategy to upgrade Tiki from 14.2 to 18.3
I would say the upgrade would be worth it, as the 14.x version you are using was only a mid level release, it's not even LTS, you should at least upgrade to 15.x LTS to protect yourselves from bugs and security weaknesses.
The 15.x LTS should be an easy upgrade from the 14
Good luck Manel