You fix problems by making a new edition that fixes problems, not by making a half replacement, half confusing splatbook with different versions of the same-named things, including all the classes and the title, but still telling people they can use the fixed and un-fixed versions at the same time. That is marketing, not design.
If adventures work with either rules, I am totally fine.
If old subclasses work with minor home fixes: even better.
If at some point those old subclasses receive an update. Totally ok.
So I like the half variant because of that.
It won't be confusing for most people.
There will be 3 kinds of people:
- Using old books and not buying new books.
- Owning old books and buying the nw one, totally conscious of the changes.
- Newcomers who buy the new books which will have a big disclaimer, that books printed before 2024 need to be prepared to do some updates to subclasses. The UA already has such a disclaimer (without the receipe to fix it).
On top of that: old books won't be reprinted.
The third group might encounter minor confusion when buying old books nontheless. But my brother bought a 3e arkham horror for his 2e arkham horror game. So calling it a new edition does not necessarily prevent that from happening. Also calling it 6e might people wonder why the old 5e adventures still work fine enough with the new rule set.
So I am all for 5e with revised written in big letters on the cover and a big disaimer on a few pages so you just can't miss it.