Personally, I think you should use the latest version, and not worry about backward compatibility. I am not interested and have no sympathy for the claim that 'My host is not up to date', then move host.
Clearly you have to pick a version and work to that, and in the meantime a new version may come out. If that is the case and it has features the development team want to use, and it does not mean too much rework, then use it.
I voted for 'This should depend on dev process' but I support completely the use of the most up to date version available at time of writing. I see no reason why CI should limit feature use in the 'backward compatibility' game that can cause so many headaches.
Paul.
